This is what i got courtesy to EagleHannan
"A few weeks ago, I showed the leaked pics to some PAF personal and they agreed that top brass of PAF has always known of this project and the pictures are indeed the J-20. However, like all Pakistani acquisations, we are NOT interested in J-20 as it is. China is where the Stealth 5th generation MRCA will be bought from but that wont exactly be J-20.
The way PAF deals with and has always delath with Chinese manufacturers (JF-17s are exception) is that we let them present what they have. Then analyse and give them our own requirements and integrate our man power and share information we get from our own sources into the project.
Eaxmples: F-7MG --> F-7PG (Chinese couldnt come up with avionics so we bought it from theird party back when sun used to shine well in west for PAF)
J-10 --> J-10B
LIke I said before, we have no input so far in this J-20. A few have laid eyes on it. My source told me, it will be another J-20 --> J-20-B story when Chinese will put it on Table. Chances are the thing will NOT be on table anytime before 2015. For many reasons, including sales of J-10. Any plane operating with PAF is a free marketing for Chinese companies (I was so proud of it when an AVIC personal said it to me in the presence of PAF personal that the world trusts PAFs standards).
Chinese want to see J-10B in considerable number before even offering J-20. The money + interest of Chinese companies is in NOT offering Pakistan J-20 unless J-10B is flying with PAF in number.
PAF exercised their judgment back in 2007, PAF could either choose to go with large number of F-16s or bring in J-10B. My info on this is, Chinese clearly denied to do anything with J-10 unless the orders of F-16s are cut down. PAF did burn their boats after agreeing to it (I am glad they did. Thanks Allah for that) and sent thier team for a long tern partnership with China (Currently located in Chingdu). It was only after then that the Chinese let in PAF/PAC engineers tweak with J-10s and we saw the J-10B.
Time line for J-20 in small batch can easily be after 2016 and only then PAF might be invited to jump in.