Rolex is not listed, hence no market cap.
It says on wikipedia that the revenue was US$3 billion in 2003.
I would estimate that today the revenue is closer to US$ 10 billion.
Assume it makes 3,000 watch per day x 360 (days) x US$10,000 (average price) = US$ 10 billion.
Playing around with the different assumptions will give you other no.s.
So a range would probably be like US$ 5-15 billion.