Here is CUDA 6.0 Release Candidate that is supposed to support 2013 is now available that was released in Febuary of this year.
https://developer.nvidia.com/cuda-toolkit
NOTE: looks like this release will NOT have support for the VS 2013(VC12) compiler. The next version of the RC. The next CUDA version will have support for the VC12 compiler, with candidate builds being available this summer
Source: https://devtalk.nvidia.com/default/topic/622306/visual-studio-2013-and-nsight/?offset=23