Yes, Melissa.
You can always use a bach files, since that is just the same command run many, many times, with the necessary information edited on each line.
When you use a CSV the syntax is like this:
gam csv passwords.csv gam update user ~Email password ~Password
Where ~Email and ~Password are two of the column headers in your spreadsheet, containing the necessary information for each user.
Read the Wiki here:
In your case, the command should be
gam csv list-of-usernames.csv gam user ~Email forward off
So, your spreadsheet need only a single column of usernames (complete emails, or just the part before @ if there is only one such user). The header in the username column must be
Email, or else you must change the command I put above. Then you export the spreadsheet to a CSV and reference it correcly in the above command.