If you mean “handle” as in no lag and rendering with more than just mesh, (as in with shaders/textures, shadows etc - not to mention functionality), even the machine mentioned in the video you mentioned cant handle 1bil tris - the video is staggering and is clearly is overpowering the machine just rendering the base meshes. And since we are talking about rendering in a game engine I would say you cant render even your file on most about any machines today with room to spare to make a game from it.
As to the maximum amount before it crashes - just try it yourself, I do not know of a max count coded into the engine, and Id wager there is none - just depends on the hardware.