"I have no reasons to resign", says the mayor, and that is certainly true. One, he can't be removed from office...even if he is convicted of a crime, he keeps the job until he actually goes to jail. There is nothing in it for him to give up the power and resources he has as mayor, which can still be exploitable for his personal aims.
Of course, it would be good for Toronto if he quit, but he has never cared or pretended to care about what is good for Toronto, only its suburbs.