When they apply they can request gold.
After the battle go on strat, battles tab, expand the battle you just had, there is a box with a number in it for each player (normally 0) this is how much gold you want to send them. Fill in the amount you want to send and at the bottom click send payments.
Note: you can only send above 1000 to a player if they have requested more.
Note2: A player can request 1mil gold but you can pay them however much you want or not pay them at all
