Yep, running Cubase 8 Pro x64 on Windows 10 Pro x64 since compatibility was confirmed by Steinberg, no issues. The only thing you will need to do is upgrade to the latest version of eLicenser, run it once after the Windows 10 upgrade “as Administrator” (right-click) and let it repair itself before running Cubase.
BTW, you can’t install the downloaded Windows 10 onto a blank partition unless you want to pay for an activation key – you must do the upgrade on a working Windows 7 or 8. After that you can reinstall from scratch, and it will still be activated. If you want to keep your current Windows 7 intact you will have to create an image backup. True, you can revert the upgrade within 30 days but I would recommend a backup first.