I know that I'm sentient, and that everyone else is the same species as me, so I just assume that we're all sentient. But you're right, this is a question that's stumped philosophers for pretty much forever.

I see no reason to assume that the Turing test is a test for sentience, because there are plenty of people with mental disabilities who would fail it.

And if computations cause sentience, that opens a massive can of worms. We have billions of pretty advanced computers around the world, meaning that everything from a phone to a Roomba would be sentient. Or is it just particularly dense computations that are meaningful to humans (like a language learning model) that are sentient?

That also begs the question, what part of nature determines what a computation is? You can find all kinds of things similar to logic gates all throughout nature.

Ultimately, if we have no idea what causes sentience, I figure there's no reason to assume chatgpt is any more or less sentient than anything else. You could build a computer entirely out of marbles rolling down slopes that produces identical outputs to chatgpt, but something tells me few people would assume that the marbles have potentially achieved sentience.