I think both can be held as accurate. Thee is frequently fiction in truth, and just as often, if not more, truth in fiction.

It's a much beleaguered trope, but I've always held this is what Twain meant when he's quoted as saying, Write what you know, because it isn't limited to what we have personally experienced as much as it relates to what we imperfectly understand about the world we live in. And so therefore, what we write is written to the truth, be it simple or complex, internal to the story or external to the writer.

And sometimes, that means the only truth in a story is the one you tell yourself.