TG doesn't support external renderers, but there are many ...
RenderMan, Lux, VRay, Maxwell, Mitsuba, Octane, Arnold, Redshift, Indigo, Cycles from Blender and more.
A render engine takes scene input and converts it into the final image representation. Things like shader implementations are usually unique to the engine, so you usually have to shade for the engine you are using (for example, TG's surface layers, etc. work only in TG) but image maps are typically widely supported.
You couldn't use this (or any other engine) in TG because TG is not written to support external engines. But many packages are (Max, Maya, Modo, Lightwave, Blender, etc., etc.) all support the use of external render engines.
Some renderers are better at certain things than others, so a person could choose the rendering engine that best suits their needs and preferences.
This particular rendering engine that Yossam posted about is a "real time" render - claiming to support real-time GI and PBR surfacing (Physically Based) in real time. I don't know anything more about it than that - never heard of it before.