I would accept the offer. If you count a dollar a second, for 8 hours, you can count up to 8×60×60 or 28800 dollars each day. The 7 days a week part is not needed to calculate since that means you can count for 8 hours for each day of the week. To count 1 billion dollars with 28800 dollars a day, it would take about 34722.22... days to count it all, or about 95.12 years to count every last dollar. The thing is, the question never said I had to count or use it all, so I would use as much as I needed, counted the receipt, and left the rest.
