I think the capacity of the lower half of the stadium they're using is just under 7000. The game on the upcoming weekend has 1300 tickets left on ticketmaster. So looking at around 5700 right now. Safe to say 6000+ is a good bet?
Again going by ticketmaster availability, looks like the highest availability of any game is in the 2600 range, so there are roughly 4000 seats already spoken for, for all remaining games.
I think in these early days, Calgary is the one trouble spot, less than 4000 for the opener. Halifax, York and Hamilton all have few tickets left for the spring casmpaign.