Yep, Sony has confirmed that the PS4 will support party chat for up to 8 users at once. At least, that's what social media manager Sid Shuman explained in a recent Q&A.
The question came from HITTERSAURUS-REX, who asked:
My questions is. How many people can I have in My PSN/PS4 Party Chat Room at one time.. Either us all playing Killzone Shadow Fall or playing another title, watching a video, listening to music or just hanging out in our party chat room while we are all online? What Is the Max Number Allowed on PSN?
Mr. Shuman responded with "Party Voice Chat will support up to 8 players on PS4, like PS Vita.".
That's confirmation enough for us, but there's nothing stopping you clicking here to read more of the Q&A session.