How much do you think should I pay to have this confirmed?
And is it possible to pay when I already received the funds?
You are the receiver, you shouldn't have payed anything... It should have been the sender that added a sufficiently high fee.
In your case: the transaction is 1109 bytes, my node tells me the optimal fee for a 95% chance of getting a confirmation in ~30 minutes is 353 sat/byte
So => 1109 byte * 353 sat/byte = 391477 satoshi's = 0.00391477. So, the sender *SHOULD* have payed a fee of 0.004
BTC instead of 0.0007
BTC. He cheaped out on the fee, and the end result is that you're in trouble.
Technically, there is no way to pay the fee after the transaction is confirmed. Your only options were listed in my first post.