I have the nvidia drivers install cuda not showing up
You’ll have to describe how and what cuda is installed on your system…
I see cuda 7.5 and 9 packages for LEAP 15 (no 8, various other versions).
What guide you may be following to install cuda and configure blender (provide link)
I see according to various Debian articles that a modprobe command <may> be necessary (on Debian provided with a package install).