The first parameter of findfile is the path, the second is the filenames you want to match (can include wildcars), so change the findfile to:
//echo -a Total: $findfile(w:\gcapture\,gunz*,0)
Will return the total files that start with "gunz" in folder w:\gcapture\
Note that if you don't specify it, $findfile will look into subfolders as well, so it will look in all subfolders of w:\gcapture for matches. If you only want to find the matches of the first level of folders, you need to specify the depth, which is the forth parameter.
//echo -a Total: $findfile(w:\gcapture\,gunz*,0,1)
Will return the total number of files starting with "gunz" in the folder w:\gcapture without looking in subfolders of that folder.
