He's not much help; he refuses to talk about his work until he's drunk, which he's not yet. Oy.
Hint 2
In the meantime, though, he can tell you a lot more about Joe Gould and the man who wrote about him, Joseph Mitchell. Joey knows that name, and so do you if you played the last game, Blackwell Unbound.
Hint 3
When you've learned all you can from Claude and he starts to repeat himself, leave. You'll see him again at the gallery. In the meantime, this is a good time to find out more about Frank's death from Monique and visit the Meltzer Foundation, if you haven't yet.