] Does anyone know how much a writer could expect to earn with a novel? I haven't been able to find this information anywhere.

Could it be possible that this is a homework question?

If not, please, I apologize in advance for the supposition. If you want an answer, perhaps you might want to read some JA letters, there she herself comments how much did she earned with her novels. Also The Cambridge Companion to JA has a whole chapter dedicated to this subject.