If I move an image to a gallery...

Let's say I submit an image on a video game page. Automatically, this image is added to my username. Now, if I move this image to a gallery still inside my username's account while the said image hasn't been approved yet, will the submission be cancelled (like, connection lost or something) ?

Nah, you can even delete it if you want. Even if the image hasn't been approved and you delete it from your profile, it's probably still floating around on the server somewhere. That's just how sites are usually set up to work.