@kanoga88
If it's not an application update, but an iOS software update, @BlakeRichardson is correct.
Also, iOS software update has a file size of 1GB or more and it takes a lot of time to download it to the mobile device.
If you see "Settings - General - iPad Storage", you can check how much iOS software update file has been downloaded.
If the iOS software update command is normally push to the device, this download file is created and the capacity increases.