In 2009 he was flying 700,000 miles per year. Last year he hit 17 million flown, which would mean 7 million in 5 years or 1.4 million per year — twice his earlier pace. That would be 3835 miles per day which would require flying literally a third of the hours in each year.
Source: Next Week Tom Stuker Will Fly His 18 Millionth Mile on United Airlines