Thanks a ton cudawarped! It worked!! 
Solution:
From the NVIDIA Video Codec SDK folder
Video_Codec_SDK_11.0.10/Interface/
I copied the three header files
cuviddec.h
nvcuvid.h
nvEncodeAPI.h
to the local folder
/usr/local/cuda/targets/x86_64-linux/include/
Result:
I finally get the NVCUVID to show up during the configuration of openCV!
NVIDIA CUDA: YES (ver 11.5, CUFFT CUBLAS **NVCUVID**)