Its very likely a lot less scientific than you think. AC basically throws a certain amount of capacity into the market, and then, at the margin, adjusts it. Spikes are dealt with through rationing, that is, raising fares or reducing inventory in low fare buckets so only those who want to pay $$$ can make a trip. Its not merely a problem in queuing theory or graph optimization.

In AC's case, they have a whole ton of non or minimal-revenue passengers which don't even enter into consideration for planning purposes, ie: Aeroplan reward tickets, employees, etc.

Its fairly rare in the AC schedule to see any specific augmentations of routes to coincide with specific events. For instance, there aren't extra flights over Chinese New Years, even though, we know anecdotally that the planes are usually heavily overbooked.

Most of the decision making at AC likely involves small incremental tradeoffs. For instance, YXE-YYZ can be served with an E75, E90, or 319. YQR-YYZ can also be served with the same. If YXE-YYZ produces higher yields than YQR-YYZ, then YQR will get downgauged to an E75, while YXE might get upgauged to an E90 or 319. Price-based rationing works extremely well at pushing away excess traffic, as does flying seats empty pushes away excess capacity.