If you are looking for an authentic pub atmosphere where every single person will be cheering for England (or else) your best bet is probably the Duke of Gloucester at Yonge and Charles, just south of Bloor. Be warned that where I say "authentic" some people might say "divey" and it's draught beer and traditional pub grub all the way -- including deep fried mars bars.
But I'm pretty sure the place will be packed.
I went to Scallywags on St Clare and Younge to watch the last game .. it is a ZOO!!! The food is terrible, but I think it is the place to watch the game, if you like being sandwiched amongst tons of getting-drunk fans. It is fun.
OR, I have also being going to Cafe Diplomatico http://www.diplomatico.ca/ in little Italy, less atmosphere but a good place too.