The games industry is worth more than the film and music industry combined, however I would imagine the royalties aren't great. Most of the music used in games is specially written, so the likes of Rockstar which licences popular music is the exception rather than the rule. With hundreds of songs used in the latest GTA, I reckon between $5k and $10k per song, depending on the artist. A lot of older artists will probably just be happy to be featured as it puts their music in front of a new, and massive audience.