Next week, the console goes on sale in Sony's backyard, Japan, which should lead to another large boost in sales. So far, the console is available in North America and across Europe and Latin America.
Microsoft has seen strong sales for their new Xbox One, as well, but it appears to be falling back significantly with unit sales at 3.4 million (most recent estimate).
Nintendo's Wii U, released in November 2012 giving it a one year head start, has only seen 5.7 million unit sales, with the PS4 expected to surpass it next week.