Air International wrote in their T-50 article (March issue 2010):
"The largest type of armament likely to be carried by PAK FA are long-range air-to-air missiles, probably of '810' type (4.2m long), multi-purpose air-to-ground missiles such as the Kh-38M (4.2m long) and the Kh-58UShK (4.2m long) anti-radar missile. Each of the T-50's weapon bays is estimated as 4.6 to 4.7 and 1 to 1.1m wide; two '810', Kh-38M or Kh-58UShK missiles can be placed inside one bay. Other armament types, such as K-77M medium-range air-to-air missiles, K-74 abd K-30 short-range missiles, Kh-36 anti-radar missiles and smaller bombs, with smaller dimensions can easily be placed in the bay."
Mere speculations, but gives you a hint :)