I have a friend who will hopefully be obtaining a Candadian work visa, however he has a few different job opportunities in Canada. When you obtain a visa are you able to work at more than one job? Do you have to supply letters from all these employers?

I have several more questions, but will browse through the other posts first to see if my questions are answered

Its great to have a forum like this, thank you.

Unless it is an open work permit, which is not common, the permit is generally specific to one employer position and location. Additional employment in Canada would be subject to the need for additional work permits; alternatively a single work permit can cover multiple occupations in some cases such as when it is sought in the possession of corresponding supporting Labour Market Opinions.