This! 

Wii U lifetime sales... 

yes,  the wiiU, according the VGC,(wish we had a better source..)  has sold 6.7 million lifetime,   the ps4 has sold just over 4.3 million ytd.    thats roughly 2.4 million difference, or "gap"

August, Septmember, october, November, December.   5 months.

or is this US only?   the op is kind of.. none explanitory lol

Clarification wise its Sony's Launch date to the end of this year and total shipment from both companies.  We wont know for quite a while but its fun to speculate.

If Sony can somehow ramp up production for Q3 and Q4 and have a price cut in there somewhere i can see them pushing a high number, Somewhere in the 17-19m range.

Right, but it's comparing what the PS4 is going to make at the end of this year to what the Wii U is going to make in it's entire life time. So like 13-14 maybe 15 million to the life of the Wii U, which at this point is looking to be 25 millionish if the numbers continue. 

To rephrase the OPs question: Will the PS4 by the end of 2014 have sold more than the Wii U will ever sell in its life, or not?

So you think they are going to doubt what they have sold so far? Wow, that to me is optimistic considering how well the PS4 started and has trailed off lately.

Not.

hmm that is such a rediculous question i didnt even consider it that way..  lol  unless nintendo drops the wiiU its going to sell more. one would hope..   below 15-16 million lifetime would be horrendous(and thats a conservative estimate for sony at the end of the year..   september is such a big ordeal its hard to tell exactly what will come of it)

Well the first six months have exceeded anything that Sony planned for.  That and reduced cost of the console tells me they are free to overproduce and channel stuff and not worry about the after effects since the console is still in demand.