It's very hard to break into game development jobs, however an entry level programmer in the US can start out at $40,000 + a year.
I've seen job postings for senior programmers going for $250,000 + a year.
If you develop your own games ( and they become popular ), there is a potential of making $ millions. Markus Persson ( Notch ) has earned over $237,000,000 USD from MineCraft so far. LINK