Since this is the first year with the new course and new start time no one can give a 100% sure answer. In previous years Epcot was a hard ticket event so to be able to cheer from Epcot you had to buy the after party ticket. This year most runners will get to Epcot before opening. When I did the 5K and 10K that ran through Epcot before opening spectators were not allowed in the park. They could be at the international gateway entrance area, paths around Boardwalk, Beach, Yacht, Swan, and Dolphin, or could be a the finish. You couldn't actually be inside the park. I imagine since this race should be done by park opening they won't allow people there to cheer. It is also different then Magic Kingdom is that there is no easy way to get people in and out and only see racers with out them disappearing and skipping out on paying for the day.