Is Eren from "Attack on Titan" dead?

He's still alive. He's a titan shifter so after he turns into a titan he can turn back. (Well has to be pulled out mostly but yeah)

I'll assume you haven't finished the series yet. No, he's not dead, he's the protagonist after all. Not that often that they die so early on.
Anyway, yeah, Eren became a titan. He'll turn back to normal soon enough.