XCode 4.6.3 comes with iOS6.1, hence XCode will not detect your iOS7 device. It can detect any device with iOS version <= iOS6.1 and allow you to use it for development.
If it is just matter of installing app on your iPad, you can use iTunes for that. But if you want to connect device to XCode for debugging or using Instruments then you will need to upgrade to XCode5.
EDIT
There seems to be this workaround that has worked for few people. But it still requires installing Xcode 5. Xcode does not recognise a device with higher iOS version than available with it.
Hope that helps!