Depending on their level of success? (I'm surprised this isn't a stickied thread- it's surely been asked before.)
Not much. The top 1% of writers get something like over 50% of all book royalties. (I'm not sure of the exact statistic, but it's something dismaying like that). Most writers, even some fairly successful ones, who have a half-dozen or so books published, that make it on to the NYT list and make it to paperback, and are available in a lot of places (like Costco, Target, all the big booksellers, etc.) usually have to have some other job (often it's teaching writing, sometimes they can do freelance articles, sometimes it's working in a bookstore or something) in order to earn a living, esp. with benefits. Or they have to be married to someone who has a stable job.
Your average novelist isn't going to make that much. I think the average advance is around $10k, but this number includes all the writers who are getting 6 and 7 figure advances.
anywhere from none, to billions... btw, all novels are fiction by definition... so 'fiction novel' is redundant...
