Yes, you’re using nvcc (CUDA C) flags. You need to use the equivalent nvfortran flags.
“-G”: Device debugging. Nvfortran enables this when “-g” is used. Though can also be enabled via “-gpu=debug”
“-gencode”: Use “-gpu=ccXX” where “XX” is the compute capability of the device you wish to generate code for. Note that this flag is optional if compiling on the same system as you’re targeting as the compiler will auto-detect the device.
“–maxregcount=256”: Use “-gpu=maxregcount:256”. Though “256” is the max limit already so this flag isn’t needed.