Does kintex 7 support 1553b and RS422?
Easy answer is yes,
More complicated answer
What level do you mean support ?
Do you mean on a processor on a 7 series part, or in Logic ?
Do you mean can you connect +- 12 v to an FPGA directly ?
These are different questions,
The FPGA has a set of IO voltages and current it can support,
typically these are of relatively low level 1v8 or 3v3 being standard,
So you will undoubtable need an external buffer to convert the voltage levels, provide the drive strength and the ESD isolation required.
there are many ways of implementing the algorithm of these protocols.
FPGAs are by definition Field Programable Gate Arrays
and a Gate array can do "anything" in logic,
its just a matter of the resources your implementation needs and device you choose.