Gap=No longer receiving pay checks. If you aren't actively flying for a 121, 125, or 135 carrier then it's considered a gap. A furlough is a gap. If you're furloughed with an expired written then you have to take the written again since you aren't actively practicing the material covered. He's furloughed and wants to get his ATP. It will require a new ATP written. If he gets hired by a regional tomorrow then he can go do his checkride. Since he's not employed he's currently in a gap.