In a nutshell, you can't.

Maya's fire and things of that nature can't be rendered in real time in the Unity engine, nor can its dynamics occur, well, dynamically inside of Unity.

Water? Maybe, but you'd have to bake the water as meshes every frame and import every mesh into Unity (and obviously it'd no longer be dynamic, just predetermined baked dynamics).

You can lightmap in any program and export the lightmaps to unity. But if you mean volumetric lights and specially-rendered lighting effects, no, because again, Maya's renderer handles this and it isn't something you just move into Unity.

while you can't use maya dynamics, game engines used to be able to handle maya particles converted to textured polys for things like dust clouds when characters walk and flasy sword sweeps etc. not tried it in unity but maybe worth a shot.