Plenty of online games have failed to maintain a consistent Steamcharts number over time; GTA Online isn't one of them.
Only a few games reach over 100,000 players concurrently in Steamcharts and even fewer manage to keep those players for a few months. Examples of games that have done the former and not the latter include Realm Royale and Fall Guys, which both lost a huge amount of their playerbase within two to three months.
By comparison, GTA Online consistently reaches over 100,000 players a day, sometimes over 200,000. It is important to note that these numbers are solely for Steamcharts (and are represented by GTA 5, the base game of GTA Online). If a player is playing GTA Online on other platforms or methods outside of Steam, it won't be represented here.
GTA Online's impressive Steamcharts numbers
GTA Online launched in April 2015 for Steam platforms. Its peak numbers were 360,761 and its average players was 192,714 for that month. GTA Online won't ever hit the same high as that month, but virtually all games suffer that fate. However, GTA Online's numbers aren't that low in the present day (118,917.4 average players and 258,539 players at a peak, according to Steamcharts), which makes it mightily impressive.
The ups and downs of GTA Online's Steamcharts numbers
Surprisingly, it wasn't all that positive at the start. By the end of 2015, there were 43,874.7 players on average, with 84,558 players at its peak. Now, some players might just play GTA 5 and not online, but seeing as though GTA Online consistently gets updates and the base game doesn't, comparing the two numbers will be focused on online, as it makes more sense later on.
By the end of 2015, GTA Online had the Halloween Surprise DLC, Festive Surprise 2015 DLC, Executives, Other Criminals, Freemode Events, Lowriders, and, of course, the GTA Online Heists updates. Most of these updates were decent additions to GTA Online's longevity, with the last one being the most crucial (seeing as how the game's heists are seen as its selling point).
2016 was a big year for GTA Online. The Import/Export update was a big one, as was the Cunning Stunts update (alongside with other racing updates) and Bikers update. 2016 focused a lot on vehicles, which helped promote more activities in the game outside of killing one another. By the end of 2016, the playerbase grew to 61,843.7 players on average and a number of 126,681 players at its peak, according to Steamcharts.
A consistent 2017 to mid-2019 numbers on Steamcharts
There would be some more ups and downs for GTA Online on Steamcharts in the upcoming years. 2017's most noteworthy update was Gunrunning, which introduced new bunkers, the infamous Oppressor, and more uses for weapons (honorary mention towards Doomsday Heist, Transform Races, Smuggler's Run, and Special Vehicle Circuit).
December 2017 was the high point of 2017 with 78,066 players on average and a peak player count of 170,316 according to Steamcharts. It would go down for quite a bit until July 2018, when the average player count was 80,395.3, and the peak player count was 162,021, according to Steamcharts.
Red Dead Redemption 2 was being heavily developed and was released in 2018, so GTA Online didn't get too many updates as one might expect (Red Dead Redemption 2 is made by Rockstar Games). July 2018 introduced the After Hours update, which added some nifty businesses so players could earn passive money. Other than that, 2018 also ended with the Arena Wars update.
By now, Rockstar Games has had a successful game that has maintained a huge fanbase on Steamcharts (and on platforms other than Steam). The updates were consistent and usually helped make the game feel more diverse in which activity the player could choose to do. Its peak players were constantly above 80,000, and its average players were above 40,000 (still low compared to today).
With minor updates here and there, 2019 coasted on by without a big update to revitalize GTA Online. Despite this, the previous updates kept players busy, and the numbers were slowly going up. That would change when the Diamond Casino & Resort update would significantly boost GTA Online's numbers on Steamcharts.
Another growth period
GTA Online has surprisingly maintained a sizable playerbase despite being released for over half a decade by this point. As mentioned earlier, some games like Realm Royale and Fall Guys lost most of their fanbase in about a month. Yet, GTA Online wasn't done with its impressive numbers; no, in fact, it was about to grow even larger than one would expect of a game this old.
The Diamond Casino & Resort update was massive for GTA Online's success on Steamcharts. It nearly doubled the average players and peak player count (average players: 56,717.7 to 92,617.6; peak: 109,164 to 197,555). From then on, 2019 would close out on 97,777 average players and a peak player count of 204,137.
2020 would continue the success of 2019, with another high of 267,360 peak players in February 2020 (average players was 142,724.5). There was no big update like the Diamond Casino & Resort update around this time, for the next huge update would be released around December, with the Cayo Perico Heist update.
2020 would end on an average player count of 106,914.3 and a peak player count of 258,539 players in December 2020. While 2021's impressive numbers are yet to be fully realized, the current average players in early January is 118,917.4 (no peak numbers released).
The quality of GTA Online's updates is simply astonishing. For a game that's been out for nearly seven years, it's continuing to get good update after good update. In fact, GTA Online is frequently number five on the most played games on Steamcharts (and is the 10th in the category of the top records).