Republican pickups number 64 gross, but the net must subtract Democrat pickups, which were 3: the at-large seat in Delaware vacated by primary defeated Mike Castle in the Senate race, Abercrombie's seat in Hawaii only very temporarily occupied by a Republican, and Cao's seat in Louisiana, who lost as the only Republican voting for Obamacare.
So net 61 Republican pickups, as shown at Real Clear Politics, with 8 races still not called.