Federal Employee demographics are published by the Office of Personnel Management with latest dataset coming from September of 2012. Government Executive is currently updating a list of all federal agencies who have publicly addressed the need for furloughs. A few agencies have issued official furlough letters with set terms, while some simply guess they may "need to furlough [insert vague large sounding number] for [insert indeterminate number of days]".
In order to break down our analysis into something finer than $85 billion we'll need to find which of the 100+ agencies are forced to make cuts.
For this analysis we'll focus only on the agencies that are considering a furlough. Where those agencies haven't specified a length of their furlough we'll assume the average, which is 17.4 days. If an agency doesn't give an exact number of potentially affected employees we'll assume the worst case: the entire agency.
Using the above assumptions I've derived an agency adjusted furlough scenario that affects 693,926 employees at the cost (savings) of $49.9 billion over the next year. Note the following is thus a conservative estimate as these numbers are higher than the $46 billion on the books for 2013.