Hi @sanrajbhar,
Do you want to migrate data from your On-Premise SQL Server to your Azure SQL Server with all connection details (these connections within PowerApps app) intact to respective tables?
When you created a connection to your On-Premise SQL Server from your PowerApps app, it used the On-Premise Data Gateway to create this connection. But when you created a connection to your Azure SQL Server (cloud service), it don't need the On-Premise Data Gateway. The two types of connection contains different connection infomation (Username, Password, Authentication type, Server name,etc.)
If you want to migrate data from your On-Premise SQL Server to your Azure SQL Server with all connection details intact to respective tables, I afraid that there is no way to achieve your needs in PowerApps currently.
If you would like this feature to be added in PowerApps, please submit an idea to PowerApps Ideas Forum:
https://powerusers.microsoft.com/t5/PowerApps-Ideas/idb-p/PowerAppsIdeas
Best regards,
Kris