Use the =SUBTOTAL() formula to only sum data in visible rows.
Say you have names in A2:A20 and revenue in B2:B20
in your sum (say B25)
=SUBTOTAL(109,B2:B20)
Without the filter, this will give you a grand total, when filtered, only the visible cells are summed.
Alternatively, you can select all your data and create a pivot table. Put the names in 'rows' or 'row labels' (depends on XL version) and the revenue amounts in the 'data' field. This will give you a sum for each name in the list.
HTH