How to update the Submission date data of the form in JotFormm database

Will the {DATE} always be the same as the "Submission Date" added to the JotForm database?

The Submission date is dependent on your username Time Zone. You can follow the user guide to change/update your form Submission Date data.

User guide: How-to-Change-Submission-Date-to-a-Different-Format-and-Timezone

So the {DATE} field will not necessarily be the same to the Submission since the {DATE} data will get it from the browser device the form was submitted during that time.

I hope this help. Let us know if you need further assistance.