Re: My brother is illegal in Canada, is it effect on my visitor visa?
First, yes, you have to list him, even if you don't know his address in Canada. Not listing him can get you banned if CIC finds out.
As far as it effecting your visitor's visa... I don't have any experience to answer this question, other than to say, yes I would imagine it would negatively effect your chances for a visa. CIC may think you're really planning to join your brother illegally in Canada.