from hong kong airport to citygate outlet. What bus no. ?

From the airport to Citygate Outlets, you can take bus no. S1 at Passenger Terminal Building, Cheong Tat Road, and get off at Tung Chung Station. After arriving, walk northeast around 110 yards and you will see the destination directly.

From Citygate Outlets to Tsim Sha Tsui, take Tung Chung Line at Tung Chung Station, and get to Nam Cheong Station. Then transfer to West Rail Line to East Tsim Sha Tsui Station, Exit N5. Then walk north along Nathan Road around 110 yards.