Will my son get the Xbox One update added to his Xbox 360 map?

My son has an Xbox 360 minecraft edition and he wants an Xbox One for Christmas.

The problem is that he has a map that he spend lots of time building (it's in
survival) and he is wondering when he will transfer the map will he get all the updates that are on Xbox One added to his world. E.g will his world become bigger.

Yes, as long as he has it saved on Xbox cloud, or has a storage device that is compatable with both systems. Flash drives work perfect for moving games around system to system.