How many miles are 8 units?

Units are not a consistent form of measure and are used to delineate measure. (I.e. one unit of a predetermined size is exactly equivalent to another unit, but until the unit is defined in context, it has no meaning.)

Therefore your answer is indeterminate.

However, if by units you mean AU or Astronomical Units, your answer is

8 * 92,955,887.6 miles per AU = 743,647,100.8 AU