Client has booked UA r/t to SFO;
-assuming a legit fare, can SE's u/g via phone or is gate standby the only option? Do we use AC certs or, as outbound is Feb 21, could Cdn stickers be applicable?
If it is UA metal, then there is no way you can upgrade beside for the operational thing. I suppose with the amount of 1K that UA has, it will be hard to get upgraded and the F cabin of UA on A320 {YVR-SFO} is smaller than AC's. 12 F seats on UA vs. 24 J seats on AC.
If it is AC metal but booked on UA flight numbers, the best you can do is try at the gate using your SE status. However, it will be hard since the fare codes between UA and AC is totally different.
Bottom line is you can only upgrade on the carrier that you have status on. {1K on UA, SE on AC...}. Agents seem pretty strict in implementing this rule.
The best you could do as a * Gold is to confirm a Economy Plus seat now, it's first come first serve. I would suggest you do that now. It's only a 2hr flight so I think it'll be acceptable.