Stoke are expecting a 28,000 sell out for the game and the tie could be worth up to £400,000 - it might even get on television.
Gislason said: "A cup run was always going to be very important financially to us - that's why we never saw the competition as a sideshow.
"The league is obviously our priority but the money from the cup is a huge help not just to our overall finances, but also to our aims to help Tony Pulis strengthen his squad.
"The money is critical - it will help stabilise our finances for this season and help us to cope with the loss of revenue from ITV Digital.
"So far we have collected around £125,000 from winning in rounds three and four on top of around £125,000 from the gate receipts from Wigan and Bournemouth.
"We are not going to put a figure on the money available to Tony Pulis but there is money available.
"Bringing in new players is not always a question of having money. It's also a question of the availability of the right players, whether they are willing to come here and, of course, whether the manager thinks they will enhance his squad and are good value."