We will know with the next quarterly report (unless they lump the numbers together, which I fear they will do).
1.4m per month is out of question, though.
They started in August and given how "simple" the innards of the PS4 look like, they could have reached maximum capacity early september.
With 300k units per week as a ceiling, which would mean roughly 17 weeks of production and 5.1mio units end of december. That number is "dead on" if we assume 2-3 weeks of production on ships somewhere and 4.2mio sold. I'm more inclined to assume that Sony flew in around one week for Xmas, so around 1.15mio units per month is a reasonable number. (1.4mio/month would also seriously clash with Sony's 5mio sold prediction by end of march).