@TSNScianitti just tweeted television ratings for game one for the Raptors at home against the Brooklyn Nets. Average 539K, "peaking at over 2.17 million unique views." Compared to the CFL the unique views are impressive, but the average is nothing special. That game and all CFL games are on TSN, so there's no broadcast versus cable effects.
As a way of comparison, in 2012, the BC Saskatchewan pre-season game had over 400,000 viewers, whereas the Ticats Argos pre-season game has 336,000 viewers. Generally I think the CFL should broadcast more pre-season games, or at least the Saskatchewan ones.
The CFL has the advantage for advertisers that more fans are in Alberta and Saskatchewan, where males make more on average and the median. I'd be curious to see how Toronto centric viewership was.