Just want to know your opinion.

Can Witcher 3 outsell AC: Unity and be top 6 sales on PS4?
Sales number at week 4 are very close, so I guess that Witcher has chance.

Easy.

Selling another 1.5 million on PS4 alone might be tough, but it is certainly possible with it being close to 2 million after just 4 weeks. Should be at 2 million by week 6. ACU sold nearly a million from weeks 5-10 (thanks to the holiday time period). TW3 is not likely to do that. I will vote yes, because maybe the power of positive thinking will make it happen. I will be someone who buys TW3 who never bought ACU, so I will be helping it along on its goal.

Yes, I think so. AC Unity could have done better but it came out when the PS4's install base was smaller and the game itself got a lot of criticism for all the glitches.