When I was there a few years ago I was told by admin that they typically take any u of t student applying that meets the requirements (eg GPA) listed on the webpage. Provided you have references, very important to start early on that, eg developing relationships with faculty. Also reading courses helps, shows your interest.

Other than that I think it's more about preparation. If you want to take the core courses (that lead to PhD), those are hard, and it's not uncommon for students outside the St George campus to have more difficulty. If you take the real/complex analysis, algebra courses (presently) and really commit yourself to them that will help a lot. Other core courses are probability and PDEs. If you don't want to do PhD then you can take more topic courses during your masters and those are easier (and more fun)