Avengers: Endgame - 15 Biggest Rumours From 4Chan & Reddit Supposed "Leaks"
2. Thanos Will Die (Possibly Several Times)
The Leak
According to that same comprehensive "leaked" breakdown, Thanos will be killed in the first mission by the Avengers, having been weakened by the Decimation and without a working Gauntlet. The Avengers will then head to the past to undo the Decimation after a time jump, and meet Thanos again.
Ultimately, he'll die a second time, according to that leak - which fits with most leaks saying he'll die at the end of the movie. It's just HOW he dies that's the issue. One leaker claims he'll die at least three times, another says he'll actually meet Death and convince her to send him back to Earth, another claims he will destroy the Stones himself and die in the process.
Response
Given Marvel's precedent with villains, it's likely that Thanos will die. They don't have a habit of keeping too many big villains around and Thanos is a zealot with a messiah complex. There's no way he's going to be left to his own devices when the Avengers know that he wants to rebalance the universe through genocide.
So yeah, he'll die at least once.