I don’t think that this will work on any OS, at least in my experience. The best way would be to just export all variables in a shell script and run maya from that script.
Why don’t you try the following:
1. Open up a terminal
2. $ export VRAY_FOR_MAYA2016_PLUGINS_x64=/Applications/Autodesk/maya2016/vray/vrayplugins:/Applications/Yeti/bin
3. $ open /Applications/Autodesk/maya2016/Maya.app
If it works this way, we can help you set up these environment variables automatically.
Can you please check your /etc/profile and tell us if it sets the variable? It looks like Maya.env sets only these variables that are not already set by the time of starting up Maya. Thus, if you have VRAY_FOR_MAYA2016_PLUGINS_x64 defined in /etc/profile, whatever you place in Maya.env won’t make a difference.