If I'm understanding your question, yep - to eat at an Epcot restaurant, you have to be IN Epcot, and to get in Epcot, you have to buy admission.
But ... there are so many nice resort restaurants available, you don't even need to worry about being in one of the theme parks. I like another posters idea about trying a restaurant at one of the Epcot resorts - Boardwalk, Yatch and Beach Clubs, even the Swan and Dolphin might be good options.