While Atlas claims they don't staff a certain number of crews per airplane, in the last several years they have consistently staffed the airline with 9.5 Captains per airplane (classic and -400) with 12 F/Os per airplane for the classic and 14 F/O per airplane for the -400. If they park three classics I would expect the furloughs to be about 28 Captain downgrades pushing that many out the bottom.
BUT - there are faint rumors of getting (back??) at least one -400, which would equal about 24 crewmembers.