Whenever the next release is, it will likely support CUDA 11. Or alternatively, if you can compile KataGo yourself, the tip of the master branch on github already supports it.
https://github.com/lightvector/KataGoOtherwise, you should just use the OpenCL version. In fact, most people have reported that on RTX2080, the OpenCL version is *faster* than the CUDA version. Good chance the same is true for RTX30**.
So there's actually not a big reason to use CUDA - CUDA and especially CUDNN are more annoying to install, legally obtaining them they require you to agree to more annoying NVIDIA license terms, and they're not even clearly better than the custom hand-written OpenCL code.