As for bar gigs... anywhere from nothing to a small cut of the drink sales... or door sales if there's a cover charge. Sometimes you might get a flat fee. Sometimes you'll be lucky if they allow people to throw spare change into your guitar case.
If you're, like, a working musician at a jazz club or a studio space or something that's a different story... one that I won't tell here. Being a "Lifer" isn't easy unless you have celebrity status within the industry and have even been heard of by ordinary music fans. But anyways....
If you're talking about rock clubs like in L.A. (i.e. the Whisky or the Roxy on the Sunset Strip) and sizeable-enough cities (Vegas barely seems to qualify, though it has budding potential; no, System of a Down playing at the Hard Rock Hotel & Casino in front of a bunch of tourists does not count as a 'local scene') you have to guarantee that you'll draw a sizeable enough crowd for them to make $$$ (or else you'll never play the joint again), and often you have to hit the streets and sell the tickets yourself (usually to people you know or, at best, friends of friends of friends, etc.). I guess a lot of bands have been benefitting from this MySpace.com thingy and have been drawing in people that they wouldn't normally come into contact with on the street or in the scene.
But even in L.A., most the bands I knew were constantly grousing about the dismal cut they'd get from playing the clubs. I guess the higher up you are on the scene totem pole, the less you get screwed. Although L.A.'s pretty cutthroat... maybe they're kinder and gentler in somewhere like Omaha or Austin or something.
If you're taking your band on tour you'll be living off of 30-cent hamburgers and will be hoping that you can make enough money to have enough gasoline to make it home. A lot of old punks say the reason that the Ramones died off is because of all the horrible food they had to live off of back when nobody but a few thousand weirdos in New York, Cleveland, Boston, Los Angeles, and London knew who they were. As in, way substandard even by today's typical American diet.
If you stick around locally, as the Ramones did for their first couple of years... let's just say it won't cover your band expenses, let alone make anyone a living. Unless you want to live on the streets or in abandoned buildings like some of the Ramones did, or like three out of four of the Sex Pistols did. Those guys were pioneers in that virtually nobody in New York or in London attempted to live off of ultra-marginal rock music endeavors in the mid-1970s. You were either a hobbyist playing popular covers in bars full of normal people on the one hand or you were a working professional or a star.
But even today, it is a struggle and you have to be committed if you want to get anywhere that even resembles anywhere.
Things might change if you ink yourself a record deal, though if it's with an indie, chances are you won't even be able to save up for retirement on what you'll be making, let alone feed a kid... you'll be lucky to make rent. As for a sizeable or major label... don't get your hopes too high up unless your first single shoots to #12 or something or unless you garner a die-hard cult following that packs theater-sized venues in almost every town you hit. If neither of those things happen they'll neglect you and eventually jettison you.
Ah... but we can dream, can we not? :D
