Is it still possible to update my iPad from iOS 7.0.4 to IOS 7.1.2 and not to iOS 8?
Nope. It's not possible on any iPad or iPhone because Apple stops signing the older iOS versions after newer ones are released. It's impossible to upgrade to iOS 7.1.2

Three options you have right now


Upgrade to iOS 8.1 [download the firmware separately and update before Apple stops signing] 
Upgrade to iOS 8.1.1 from iTunes
Stay on iOS 7.0.4


iOS 8.1 has jailbreak, so this could be your chance to upgrade before the window closes.