Q: My son got a new iPad today but on his old one he wasn't signed into the Game Center on his old iPad. If I sign in now will it save his games or erase it all

Hi Nicole,
 

Thanks for participating in the Apple Support Communities.
 

It sounds like you want to save your son's progress in his iOS games so he can continue on a new iPad.
 

I recommend using the steps in the following article to transfer the contents of the old iPad to the new one: Transfer content from an iPhone, iPad, or iPod touch to a new device. This will make sure all of the app data is carried over to the new iPad.
 

Game Center is used for multiplayer or social features like achievements and leaderboards and isn't intended to transfer game data.
 

All the best.