As title , please help !
and anyone can give example or refer link ??
And there is another one in development by Funcom/ArtPlant as well (still in development, will release later this year). Plus there are a few others in development (virtual worlds/MMOs) but I’m bound by NDAs to not name them just yet. But the point is that Unity is definitely capable of making a virtual world or MMO front-end! 
How many people number that MMO Kit support ???
There is no MMO Kit.
Those games, if you mean that, support as much as their servers support. The client (the thing for which Unity is used) is not related in any way to the amount of parallel users supported normally.