Hi, If I delete all my pictures off my phone will it still stay in my iCloud because it is backed up?

If you include photos in the iCloud backup, the photos will remain in the backup for only as long as it takes to backup two more times. iCloud stores your two most recent backups, therefore, if you backup today, delete all of the photos, backup tomorrow and then backup the next day, the backup that contains the photos will have been deleted.

What you should do is offload your photos to a computer for safe keeping rather than count on keeping them in an iCloud backup because storing them in a backup is not a permanent solution.

Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

Personal opinion here, I would not use iCloud photos either. That is not true off device storage. It is a syncing service only