You can customize the email template through Settings->Notifications.
Not through the gift_card.liquid you have screenshotted.
If you need any further help please let us know.
Understand that. But however, if I add my logo to the to my email templates, the image of Gift Card (yellow card with ribbon) will not show. I would only allow to use the logo or the image by default.
And here, I would like to find a solution to keep both the logo & the image. Would you able to advice?