Baltar, Tigh, Adama, Apollo, and Roslin are discussing how many know the Cylons now appear human. At 22:40 Tigh indicates that only the five of them and "three Marines" know this. At 2:20:27 of the pilot, Tigh and Adama discuss this fact in a corridor while a medic attends to Adama's facial wound. There are multiple other people walking by when this discussion takes place, so upwards of five to ten others could know.