SharePoint 2013 migration issue

Hi All,

We are in SharePoint migration process. We are migrating site collections to 2013 env from 2010 & 2013 env (OnPremise). We are migrating site collections via Sharegate. The first phase of migration is done from 2010 to 2013 but the migration is not success (incomplete). But the WSS_Content db size is 160GB. So my question is:

1) Do we need to delete the present content database to re-start the migration?

2) Or can we overrite it?

3) Before migration, do we need to create the same site collection in 2013 env?

Kindly help....

 

-Thanks, 

Nagabhushan