Can I use an Air Canada gift card to pay the "co-pay" on award ticket using AC points on the AC website if the flights are on another Star Alliance carrier?

Context: I'm looking at two award tickets using AC points on flights from VIE to ORD to DFW on Austrian and United Airlines. 80k points required. To get the 80k points, I can transfer 70k Chase points using the current 1:1.15 bonus. But if I transfer 75k Chase points, the bonus ration is 1:1.2 so I would get 90K AC points. If I do that, can I first use 10k of the points to buy a $100 AC e-gift card, and then use the gift card to pay a portion of the co-pay on the award tickets? Or is the gift card only good on AC flights?