CUDA Fortran has been available since 2009 at least in the PGI compiler. Support for CUDA is also coming to new flang (LLVM Flang Begins Seeing NVIDIA CUDA Fortran Support - Phoronix). Unfortunately, the pgfortran compiler (now nvfortran) is stuck at the level of F2003 support. This was also one of the gripes LLNL had (An evaluation of risks associated with relying on Fortran for mission critical codes for the next 15 years):
Even when a technology provider has an in-house Fortran compiler team that supports advanced hardware, such as the case for the NVIDIA nvfortran compiler, the lack of timely and robust support for “modern Fortran” has proven a major hurdle.