Hello @ksmoreno,
You would need an ArcGIS Enterprise organization, the Oracle database Geodatabase enabled, and registered with your ArcGIS Enterprise organization. From there you can publish your data as a feature service to your ArcGIS Enterprise organization and point your survey to that feature service. In this scenario when you submit a survey from Survey123 the data will be sent directly back to your Oracle database.
As for populating answers based on the data from the Oracle database assuming the same configuration as above you can enable the Inbox on your Survey123 survey and will allow the ability to edit the existing data in the database. If you don't want to edit the existing data but want the same data in a new table/layer you can publish your data as a feature class like before but still keep your Survey123 survey pointing to a different feature service. From there with our 3.16 release of Survey123 we released a feature called pulldata(@layer) that let's you query data from another feature service to pull into your survey.
Thank you,
Zach