Does generator power cord gauge have to be the same as the power inlets gauge?
9500 watts is about 40 AMPS at 240v. 8 gauge is good for 40 amps even in a cable. You can always use wires that are larger than needed, but not less.  Think thru this...most of the wiring in your house is probably 14 ga, or 12 ga. yet you are seldom using anywhere near that much on each circuit.  Same applies to your generator connection.   You might be slightly undersized for a larger generator, but for what you have now, you should be fine.