How can I go to Tian Tan Buddha if I am coming from BP International? How long is the trip

Well, according to this situation, you can take West Rail Line from Austin Station to Nam Cheong Station and Tung Chung Line to Hong Kong Station, Exit F. It takes around 20 mins with the fare of 10 HKD per person. Then walk north around 250 yards to Central Pier No.5 and take bus no.15 to the Peak directly. The return way is the same.
I searched the information on the official website. The cable car still operates now. Don't worry.