What is the maximum bitrate supported in the Can Bus?
I have found that the maximum bitRate that can be achieved is 1mb/s

Actually it's 1 Mbit/s.  That's "mega", not "milli".

how can i know the maximum bitRate supported in the CAN BUS

By reading your own words just two sentences earlier, assuming your milli versus mega error was just a typo.

In a private CAN system where you control all the nodes and the bus cabling and the length and the electrical bus interface circuits, you can go faster.  Since CAN is specified for 1 Mbit/s and most implementations break a bit time into 9-20 "time quanta", most CAN peripherals can't go much faster.  Still, look at the CAN peripheral bit rate generator carefully in your micro.  With a fast clock, you can probably run it faster than 1 Mbit/s.