Thank you for reaching out and posting this question!
It's great to see that you want to incentivize customers through gift cards. However, I'm afraid it's not possible to add more value to a gift card that customers are purchasing, as the order still needs to be processed through the online checkout. That being said, it is possible to manually issue a free gift card to every customer that purchases $50 or more in gift cards.
Another great way to incentivize customers is through loyalty programs, where they can earn rewards from their purchases and potentially increase your conversions. Have you considered integrating a loyalty program on your shop?
we specialize in gift card & loyalty store credit solutions,
I think that the best solution for your needs is a discounted gift card, this way the gift card will be worth more than its price.
Another option is to offer a BOGO incentive - buy a $50 gift card get an extra $10 gift card free.
Our platform offers those two solutions (and many more).
Check out our listing page, and feel free to reach out at email@example.com