Ask HN: How much is a typical publishing deal worth?

I know this is likely unrelated to HN directly, but it's something that's alway fascinated me. How much is an average publishing deal worth for a work of fiction? Let's say a (new) author has written a novel, and is selling it around. Let's say the novel is around 500 pages, and for some reason one of the publishers likes it and decides to take a stab and publish it. How much would said author expect to earn on something like this?

I've been curious about this ever since that Twilight author sold her first book. I'm not a writer by any stretch, but am interested in how much aspiring novelists make as compensation for a 500pg book.