RTX ray tracing makes games look better by adding realistic reflections, lighting and shadows. However, it's proprietary to NVIDIA and has yet to be used in many games. That's where Unity comes in. It offers the game engine to developers for free (sort of), offers plug-and-play modules and supports every modern platform. That would make it a lot easier for gaming studios to implement it. With more games, the RTX might develop more momentum, and NVIDIA could sell more GPUs.
Unity has its own history with ray tracing, having experimented with it back in 2015. It also teamed with District 9 director Neil Blomkamp in 2017, creating an animated series called Adam. It used effects like area lights and volumetric fog, and most impressively, rendered everything in real time, showing the potential for more realism in gaming.
Unreal recently announced ray tracing support for NVIDIA's RTX in its UE 4.22 engine, with studios able to implement basic RTX shaders and effects via DirectX 12 support. Unity has stayed mum on the issue, so while it's possible that Huang misspoke, it seems unlikely. "Probably one of the biggest stories that came out just last week is Unreal engine and Unity, both of the game engines, are going to incorporate RTX and ray tracing technology in the engine itself," he said in an earnings call. Either way, we should find out soon.