It won't receive positive reviews imo (70 Metacritic seems a fair expectation considering how most of the press has already openly decided against it before its release when it became apperent that the game is not Gears of War but a very cinematic and story driven third person shooter), but that has nothing to do with sales these days, it's not like bad reviews stopped Destiny or Watch Dogs from selling million units, nor positive reviews made Bayonetta or other niche games commercial successes.
I see The Order doing well for a few reasons, it's being marketed as (and at its core is) a third person shooter which is a genre with a huge group of fans, the game also features many fancy and cool weapons which is an other attractive point, it has a very interesting setting/story with amazing graphics and that alone will help a lot in making people wanting to play it to know what it's all about, on top of that the release window is really good and gives the game a nice spotlight in February.
I would be really surprised if the game struggles to sell at least 1m units in US+Europe during its launch period also considering the PS4 installed base.