Up to 100 individuals may attend your event. Only individuals who have attended an official TED conference (TED, TEDActive or TEDGlobal) in person may organize an event with more than 100 attendees. The primary license holder -- the individual whose name is on the application form -- must have attended a TED conference.
Having attended a TEDx event does not qualify you to host an event for more than 100 guests.
You can't have a TEDx event for more than 100 people if one of your advisors or team members is a TED Attendee.