The numbers game is always a difficult one. I think the number of Orthodox Christians in the US is much more. If you take the Orthodox Church in America, for example, there are something like 400 parishes. Estimates on the number of faithful are anywhere between 30,000 (pretty low) to 1 million (ridiculously high). Even if there are only 100 faithful per Church, that is still 40,000. However, I think that the number is nearly 100,000. It all depends on how one qualifies active, socializing, supporting member of the Church.