Don't get me wrong - being here is far from an indication that you've died, and as far as I can tell this isn't any sort of afterlife. But I've seen many instances of it, yes.

I know for a fact that one of the people from my world is dead back home; he remembers the circumstances of his death, and told me about them with no prompting at all from my end, so I have every reason to believe him. I have reason to suspect another was dead as well, though he never verified it to me directly. I've also had conversations with several people asking about such things - people who didn't know me, and had no reason to lie to me about something like that, that have told me that they died somehow in their world.