The membership is $7.99 per month.
To break even, you would need to purchase at least $40 worth of gift cards every month. You would then get $8 credited back to your credit card that you used to make the purchase.
For example:
I spend at least $50 per month at Target. I ordered 2 $25 GCs and will be credited $10 by Hotwire. I get to purchase $50 worth of Target merchandise with those GCs. If I factor in the $8 it cost me to be a member, I have a net "gain" of $2 for the month.
However, that "gain" is not money in my pocket. It's in the form of merchandise. So, unless you're planning to spend the money at any of the listed merchants anyway, there really is no sense to maintaining a membership.