If you get caught working illegally you will be sent away from Canada. Probably unable to return for a minimum of 2 years. If you are in that much financial need, you should probably start looking for a legal job, get a LMO and work visa. It is possible but does depend on your education, language skills and whether you are employable.
As for how much tax someone pays, depends on which Provence you are working in. Google Canada revenue and there is a table showing the 2011 rates of tax deductible. It is really easy to work out.
There is also EI premiums and CPP premiums to take into account. Plus in BC, there is your MSP payment too, for health care. Minimum wage in BC from May 2012 will be $10.25