Deciding who will pay the fees is as easy as changing the Payment Policy on the project.
If you see (+ Fees) in the name of the policy, then the Client will pay the fees. You can also tell at the bottom where it says 'Client Pays'
If you don't see (+ Fees) in the name, and 'Vendor Pays' at the bottom, then you (the vendor) will be paying Stripe's fees for this project.
You can change the payment policy on the project to select who'll be paying Stripe's fees.