Sorry mate, your best bet is Eaton Centre in Toronto. Shopping centres are generally closed for the holiday, save for those in tourist districts (like the Eaton Centre). Shopping on Easter Sunday is definitely not a big thing here.
I just walked along Bloor St. on my way to the GO and was surprised to see everything open, and the street full of people. Here, somehow I doubt it. Maybe hop on the GO?
easter sunday is just a day of rest and relaxation here, no shopping. kind of nice to have everyone spend time with friends and family. culture shock for omro!!!