Long haul service with new 77W likely to begin on December 1, 2014
As expected, on TPE-LAX-TPE:
http://airlineroute.net/2014/05/12/ci-lax-dec14/
Article also mentioned 318 economy & premium economy seats (total of 348 seats). I think this points to the Y cabin will be 10-abrest. You can only fit at most 300 Y and Y+ seats 9-abreast on 77W with 40 J lie-flat J seats taking up the front cabin. To go over 300 Y/Y+ seats, the rear cabin has to be 10-abreast.