So we have 3 outbox files on survey123 living on a mobile device. Someone has deleted the AGOL file for that survey so those files living on the device cannot be submitted. Is there anything I can do to link the files sitting in the outbox to another form so I can upload them? I understand I may have to re enter the data but am searching for alternatives first.
You can recover from the tablet files if they can send them to you. See here https://doc.arcgis.com/en/survey123/desktop/get-answers/troubleshootgetanswers.htm
It is worth noting that in the future, you may want to Enable Delete Protection on the Survey's Feature Layer.
(Your Feature Layer) > Settings > General > Delete Protection.
Check the "Prevent this item from being accidentally deleted."
Then in order to delete the Feature Layer, someone would need to uncheck the box in order to delete.