Standard capacity for this type of aircraft looks to be 313 passengers. Mind you those economy seats are pretty impressive:
This new SIA class of travel will offer 117 Executive Economy Class seats in a 2-3-2 configuration, with a seat pitch of 37" and a seat-back incline of 8". It will also feature a seat width of 20", a leather adjustable headrest, an innovative leg rest and foot rest, and a 9" personal video monitor for in-flight entertainment.