In "Adding a Payment Gateway + Order Success Page - Strapi Tutorial ," viewers will be guided through the process of integrating a payment gateway into their web application, along with creating an order success page. This tutorial likely builds upon previous tutorials in the series, where viewers have already set up basic E-commerce functionalities using Strapi as the backend. Key topics covered may include selecting and integrating a suitable payment gateway provider (such as Stripe or PayPal), configuring API endpoints to handle payment transactions securely, implementing client-side functionality to initiate and process payments, and redirecting users to an order success page upon successful completion of the transaction. By following this tutorial, viewers can enhance the functionality of their Strapi-powered E-commerce application, enabling seamless payment processing and providing a smooth user experience from product selection to order confirmation.