I'm also having problems with gas right now, some tokens are still stuck in my wallet and I don't know how long it will take, I also move some tokens because I have to sell them on an exchange and change them to other tokens as another option
You should replace it with a new transaction that contains more fees to pay the network. I think that will make your transaction will be placed on the priority block.
You can try this method because I have also tried that to replace my old tx that paid small fees with a new one.
Or he can cancel it anytime simply by sending a 0 ETH transaction to the same address he is sending the token from. He can refer to this
instruction if he wanted to replace the transaction fee, but I would suggest to just cancel it for it is much more simple and easier.