This looks like you mixed up compilers and solutions in the MSVS 2015 case and picked the wrong file for the CUDA_HOST_COMPILER in the MSVS 2019 case.
The CUDA_HOST_COMPILER is not
C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC/Tools/MSVC/14.16.27023/bin/Hostx64/x64/cl.exe.config
it needs to be the cl.exe itself as I explained in the linked thread above, not some .config file.
I’ve tried building all OptiX Advanced Samples in two ways just now and both worked:
1.) MSVS 2019, CUDA 10.2, OptiX 6.5.0 with CUDA_HOST_COMPILER set manually.
2.) MSVS 2019, CUDA 10.2, OptiX 6.5.0 with the FindCUDA folder and FindCUDA.cmake renamed to _FindCUDA to let CMake use its own version which finds the CUDA_HOST_COMPILER correctly.
In both cases I selected the OPTIX_INSTALL_DIR because mine is not at the default location and picked the DevIL include folder and three .lib files manually as described inside install-win.txt file.
Please delete your build folder and start from scratch. I recommend the second approach.
Newer CMake versions (I used 3.17.3) will print some developer warning about deprecated features. These can be ignored.
Note that the latest OptiX Advanced Samples have been developed with the OptiX 5.1.0 version and do not make use of the built-in triangle primitives of the OptiX 6.5.0 versions. Means these examples are not making full use of your RTX board without changes.
If you start new projects with OptiX, I would really recommend using OptiX 7 instead which has the more modern API and is generally faster.
I ported some of my OptiX Introduction examples from the OptiX Advanced Examples over to OptiX 7 and you already got those working before.
For that, please have a look at all resources listed here:
https://forums.developer.nvidia.com/t/optix-7-1-release/139962
https://forums.developer.nvidia.com/t/optix-advanced-samples-on-github/48410/4