In Ontario, we do have a Welfare Fraud "Hotline"
http://www.mcss.gov.on.ca/en/mcss/programs/social/fraud.aspx
I am not 100% sure if what Gabe is doing is 'technically' fraud though. Kind of like the same thing where you see people get their checks and head to the LCBO or convenience store and drop a wad of cash on Nevada tickets.
Now, if he is not reporting his comic sales, under reporting what he pays in rent, etc., well then we may be in different territory. I'm no lawyer though. The downside of all this is that while what he is doing is not "right", it may not be illegal and/or fraudulent either.
It's not a crime to be on Welfare in Canada.