The 33-to-1 MF ratio comes from dividing aggregate total assets ($45.93B) by total equity ($1.39B). If you do the same to IB the number appears to be a paultry 7-to-1 ($33.15B assets vs. $4.63B equity).
As for the 80-to-1 ratio, this is a total guess, but it looks like they might be taking "Securities purchased under agreements to resell" ($12.06B) plus "Securities owned" ($11.57B) and dividing that total by preferred stock ($130.6M) plus common stock ($164.9M). That yields 80-to-1. Assuming this is accurate, then IB's numbers would be (I think) "Securities purchased under agreements to resell" ($0.46B) plus "Trading assets, at fair value" ($8.88B) divided by $565.7M in common equity. This yields a 16.5-to-1 ratio.
I was also freaked out by IB's numbers initially, but I was getting my balance sheet data from Yahoo Finance, which for some reason is way off the mark.