Naruto: Is Hidan still alive during the events of Boruto? Explored
Hidan’s ambiguous fate in Naruto leaves his fate in Boruto just as ambiguous. This immortal man of the Akatsuki was a troublesome piece of work for the ninjas of the Hidden Leaf Village, even killing one of their elite ninjas with the death of Asuma Sarutobi. He ultimately was stopped by Shikamaru, seeking vengeance for his team leader - but Shikamaru didn’t actually kill Hidan.
Hidan was certainly incapacitated and out of commission for the rest of the series, but he curiously never specifically died. His body was torn apart, he was decapitated, and thrown into a pit of rubble to slowly die of starvation, but the audience never gets to see Hidan properly die. So is he dead? Possibly, possibly not - he hasn’t been especially relevant in Boruto yet, but he has been alluded to.
Hidan’s fate by the time of Boruto
This nasty missing-nin was a formidable threat in his time as an active member of the Akatsuki. His inherent immortality made him dangerous enough, but through a ritual, he could link his body and his opponent’s body together, and make any injuries on himself reflect back on his opponents.
Not that Hidan’s immortality can never fail him. Being immortal doesn’t mean being invincible. He still gets torn apart by things normal people would get torn apart by - he also can be fooled into consuming the blood of his allies, as he discovers when Shikamaru pulls a fast one on him to attack fellow Akatsuki, Kakuzu, instead.
Furthermore, Shikamaru did a good job making sure Hidan stayed down. Particularly by using explosive tags to destroy his body before burying his remains in the ground. The original Hidan is effectively a non-player for the rest of the story, and Shikamaru seems to have kept this up to the present day in Boruto.
Hidan’s legacy lives on (and so does he)
Not that Hidan goes completely forgotten. He and Deidara are later cloned for a short arc in the anime, but they don’t last long. Hidan’s clone carries on his original hatred of Shikamaru, but Shikamaru manages to ensure the clone's demise before any significant damage is done. Unlike the original, this Hidan just dies after breaking down.
Furthermore, when Hidan’s former teammate Kakazu returns from the dead for the Fourth Shinobi War, Hidan noticeably does not revive and fight in the war. Kakazu seems to be amused by the fact Hidan is still alive, presumably wasting away in the ground where Shikamaru buried him - and one can presume Hidan still is slowly starving to death in the ground by the time of Boruto's era.
Hidan had a small copycat in the form of Ryuki, who followed the same religion as Hidan. Ryuki didn’t get nearly as far though, nor did he even earn a dramatic final death - he was just arrested by the shinobi of the Hidden Leaf village, ending his conquest before it even had a chance to begin.
Hidan might be alive by the time of Boruto, but he probably won’t return to the plot anytime soon. Shikamaru’s only gotten more powerful since his fateful fight with Hidan, and as an adult and Hokage, will likely never let Hidan run loose again in the new era of Boruto.