Originally Posted by JohnneeO

Based on a personal experience, you will not need to pick up your bags in YYZ. I flew to PEK from EWR via YYZ on AC last month, and once I checked my bags in EWR, I did not see them again until PEK. My circumstances were the same as yours: originating in US, connecting in YYZ to a non-US, non-Canadian destination.