ya ... I mean your question was "how to use credit card with AXS" ... whether it is GPMC or any other credit card, it is the same pay method right? I am not referring to the cahsback of GPMC ... just the method of using AXS to pay with any credit card or debit card.
What sglandscape is pointing out is if u use debit card with AXS, once the payment is posted in a couple of days, funds will be deducted from your savings account. If you use credit card, you have ~30 days credit and need not pay until statement due date. in the meantime the funds in the savings acount earn interest. It has nothing to do with meeting min spend with AXS or getting cashback with AXS