There's been some question on exactly how many people there are:
The difficulty in counting the demonstrators is their fluid, amorphous nature. The two D.C. encampments, for example, are in busy public places downtown — McPherson Square and Freedom Plaza on Pennsylvania Avenue NW — where passersby regularly mingle with protestors. This makes sorting out protestor and bystander difficult, said Sgt. David Schlosser of the U.S. Park Police, which has jurisdiction over the two sites.
It does seem to me that the numbers at McPherson have gone up. At least there are more tents in the square now.
Read more here.