New heroes are usually tested in the PTR before Blizzard releases it into the game. All the new heroes introduced before Orisa was the same but it looks like Blizzard wants a little more time with Orisa.
The new tank is now in its testing phase on PC. According to Jeff Kaplan, Game Director of Blizzard, they planned to leave Orisa in PTR for a little while longer. He explains that there are a lot of fixes that they need to do to the heroes after players started offering their feedbacks.
He added that she will go live this month but we might only see here at the end of the month. Blizzard has already tweaked Orisa a few times now but it looks like Blizzard is still struggling to get her right.
This move might be better for us all. Remember what happen when they release Sombra in a week?