We have an unequivocal statement that Voldemort died, based on the description of the fight from Harry Potter and the Deathly Hallows.
And Harry, with the unerring skill of the Seeker, caught the wand in
his free hand as Voldemort fell backwards, arms splayed, the slit
pupils of the scarlet eyes rolling upwards. Tom Riddle hit the floor
with a mundane finality, his body feeble and shrunken, the white hands
empty, the snake-like face vacant and unknowing. Voldemort was dead,
killed by his own rebounding curse, and Harry stood with two wands in
his hand, staring down at his enemy’s shell.
And the script for the movie adaptation.
VOLDEMORT BELLOWS IN PAIN and turns, firing on Harry.
Instinctively, Harry raises his wand, countering...
... and the Elder Wand sails from Voldemort’s hand, turning
end-over-end, the spell...
... ricocheting back on him. He stands, utterly still for a moment,
his eyes on Harry, then drops.
Dead.
This is also backed up in Harry Potter and the Cursed Child, with the fact that Harry no longer feels his presence or speaks Parseltongue as further proof.
HARRY: That’s — I’m not supposed to be understanding — that’s Parseltongue.
HERMIONE: And what does it say?
HARRY: How do I . . . ? I haven’t been able to understand Parseltongue since Voldemort died.
HERMIONE: And nor has your scar hurt.
Note, however, that he's Superman dead, not Uncle Ben dead, and can be brought back with the turn of a time-turner or the flick of a wand, should Rowling need the money.
