It varies on the place, but for a staff position you're generally looking at something around 40k USD/year (entry) with some benefits (health, dental?). Although this isn't great pay, since pixel art is such a specific skill, if you're willing to relocate it's fairly easy to find work.
Most freelance jobs work around an hourly rate, which will be a higher number than if you did the division on the annual salary (taxes, private insurance, etc.). I'd say $30/hour is a fair freelance rate for pixel art.
Advertising is a solid route for an artist to make money, just be aware that it takes much more than a knowledge of art or graphic design.
P.S. Avoid Gameloft like the plague. Their 'system' results in an over 50% turnover (NYC office). To give you an idea, by the end of my 10 month employment, every artist that was there before me had quit (all but one within five months). They were giving out 1k bonuses if someone you recommended got hired, but none of us would wish that fate on an enemy, much less an acquaintance or a friend.
(I think ripping art from other games, shrinking and digitizing photos, and working with art mis-direction got us depressed.)
