can cement board be cut into narrow 6 strips and used to make wall studs?
No, it provides nothing to nail into, which is the purpose of studs and it has very limited strength if in a load bearing wall. And if you mean cutting a whole bunch of pieces and stacking them to get a 6 wide by 3.5 deep (like a 2x4) it would be a huge waste of materials and cutting blades. If you are looking for fireproof, consider metal studs. If you are looking for sound proofing, use offset stud techniques.
