I think PS3 might have a realy good sales week in japan with maybe 200.000 to 250.000 consoles sold. that with good european sales and good american sales could mean a 1 mil sales week.
so a 5 to 5.5 mil gape by the end of the year is very possible

I believe that it will be 5 million by Christmas/January (1.8 million could sell in the month of December till January 30th due to Final Fantasy japan sales).

Then the gap will get "chopped" by another million on the strength of Final Fantasy (North American launch) and Gran Turismo 5 in February/March 2010 (4 million gap).

:s but the OP said the current gap is 6.3mil or did I read it wrong?

By the end of the year.

by the end of january.

By February.

In the next 4-5 weeks the gap should fall below 5.5 million.

FFXIII will be released in Japan (and that alone should move a lot of PS3's) and the PS3 is marginally outselling the 360 on a weekly basis already.