Can Nvidia's realtime ray tracing feature be used to render with cycles in realtime?
Cycles is not a real-time renderer. It is possible to have very fast Cycles preview that could be called 'real-time' with high end graphics cards or/and extremely simple scenes, however if you need more than a couple of samples and more complex lighting with decent image resolution(that is basically every single case you would want to use Cycles for) you will not get close to 25 or 30 fully rendered frames per second. Cycles is not supposed to be real-time. It is not designed for that. RTX graphics cards can be used to render with Cycles, however at the moment no other technologies are used to do that as with any other graphics cards, so they are just a bit faster than older cards, that's all.