In May the price was ~450 USD/BTC, and on a good day BiTPay's presumed input wallet received over 2000 BTC. So, indeed, in May they were processing 1 million USD/day ... tops.
They haven t updated that number since then, though. Analysis of that wallet suggests that the USD volume that they have been processing has been decreasing with the BTC price.
AND a large fraction of that volume, as noted before, appears to be miners paying their bills, not Joe Public using bitcoins to buy stuff and services.