There's no reason to think so, IMO. There's no evidence that demonstrators/X-planes have flown for the PAK DP, and the very concept of the aircraft ('successor interceptor to the MiG-31') makes me doubtful that it represents a full-spectrum 6th generation effort.Still Russian are also working on their ''6th gen'' with PAKDP, I could say they are at more or less the same level of advancement than US in that regard. The industry side of things is lacking quite a bit tho.
If I had to rank the known 6th gen efforts, it'd look like this:
1. China: J-36 and J-XX prototypes (i.e., equivalent to U.S. EMD phase) undergoing flight tests
2. United States: F-47 and F/A-XX designs chosen (or about to be), assembly of prototypes for EMD phase about to begin
3. Italy/Japan/UK: Assembly of first GCAP/Tempest demonstrator (prototype?) has begun
4. France/Germany/Spain: Go ahead for the full development program imminent
5. Russia: They have 'concepts of a plan(e)'