It makes up part of my income, but no, it's not my job. Between Patreon and the Tapastic ad-rev, I make around 90-100$ a month on it, which is nothing to be sneezed at, but it's not enough to pay the bills. I'm a freelancing artist, so I'm always looking for work, though.
Well, attention I've gotten through my webcomic has landed me a couple of illustration-gigs that have nothing to do with the comic, so yes.
Also, I draw my comic for a love of storytelling, and would do so even if it didn't earn me a red cent. Though the fact that it DOES makes it easier to motivate the fact that I update twice a week. ^_^;