The reality is that based on the info available, we don't know what this 5th gen program actually is...so the guy saying, "it's an attempt at J-31 ToT with Turkish flavour" is either pushing an unsubstantiated opinion or is fabricating facts. That's why I brought in the JF-17/MiG-21 thing, because it's essentially the same thing - "how do you know?"
Anyways, the PAF ACM said that the 5th gen program is with AvDI in PAC. He also didn't bring up China (yet) and in an April interview said the PAF will work with Turkey in a next-gen fighter. At present the info given is pretty vague and only time will provide structure. Anything else is guesswork, which can be good at times, but is by nature tentative and not fact.