On a single form, can I use more than one payment gateway, e.g. PayPal and Stripe?

I'd like to offer customers the choice.

Unfortunately no. You cannot have 2 Payment field on the same form.

You will have to use workaround similar to what was described on this user guide:

User guide: -How-to-Create-a-Basic-Multiple-Payment-form

Here is a demo form : https://form.jotformpro.com/70983924622968