I see the CUDA NVCC flags chosen in the cmake log.  They look correct according to using:
TORCH_CUDA_ARCH_LIST="5.2;6.1;7.0;7.5+PTX"
-- Found CUDA: /usr/local/cuda (found version "11.0") 
-- Caffe2: CUDA detected: 11.0
-- Caffe2: CUDA nvcc is: /usr/local/cuda/bin/nvcc
-- Caffe2: CUDA toolkit directory: /usr/local/cuda
-- Caffe2: Header version is: 11.0
-- Found CUDNN: /usr/local/cuda/lib64/libcudnn_static.a  
-- Found cuDNN: v8.0.4  (include: /usr/local/cuda/include, library: /usr/local/cuda/lib64/libcudnn_static.a)
CMake Warning at cmake/public/utils.cmake:196 (message):
  In the future we will require one to explicitly pass TORCH_CUDA_ARCH_LIST
  to cmake instead of implicitly setting it as an env variable.  This will
  become a FATAL_ERROR in future version of pytorch.
Call Stack (most recent call first):
  cmake/public/cuda.cmake:452 (torch_cuda_get_nvcc_gencode_flag)
  cmake/Dependencies.cmake:1097 (include)
  CMakeLists.txt:469 (include)


-- Added CUDA NVCC flags for: -gencode;arch=compute_52,code=sm_52;-gencode;arch=compute_61,code=sm_61;-gencode;arch=compute_70,code=sm_70;-gencode;arch=compute_75,code=sm_75;-gencode;arch=compute_75,code=compute_75
CMake Warning at cmake/External/nccl.cmake:65 (message):
  Objcopy version is too old to support NCCL library slimming
Call Stack (most recent call first):
  cmake/Dependencies.cmake:1219 (include)
  CMakeLists.txt:469 (include)