You are technically in H-1B status with employer A if they do not revoke your status. You should respond to RFE or let employer do that to see if the petition will be approved. You can have another employer C file a new petition for you but if there is an issue with the B petition, it is likely that employer C will also get a RFE.
Answered on Apr 18th, 2012 at 2:32 PM