To create a GFS archive on tape, you need to create a GFS media pool and target a backup to tape job to it. Technically, a GFS tape job is a variant of backup to tape job. When you select a GFS media pool as target, the job schedule automatically changes to the GFS mode. For details, see Creating Backup to Tape Jobs.
As a source, you can use any backup job with any backup method: forever forward incremental, forward incremental or reversed incremental.
Do not use backup copy jobs with the GFS retention to create a GFS tape archive. The tape job do not archive the GFS restore points from disk.