I want to know whether the Optix6.5 support Geforce RTX3070 card in windows10?
Yes.
The OptiX 6.5 and newer core functionality ships with the display driver. Any driver supporting the Ampere GPU architecture should be new enough.
Please always refer to the OptiX Release Notes (link directly below the download button) for each individual OptiX SDK before setting up a development environment.
I would not recommend to use OptiX versions before OptiX 7 for new projects though.
Please search the various topics on this sub-forum which explain the benefits of the newer API.