Pushed button signal switch on
I want this: If I keep pressed the button 3 seconds, Switch on the raspberry (create that 0 signal (gnd)).

That's impossible with the capacitive touch sensor IC you've got. It emits a pulse after it's sure it detected a touch, but the pulse contains no information on how long the button was pressed.
So, you'll need a different solution. Sounds like you'd want to use one of the very many microcontrollers that have a built-in touch sensing peripheral, use that, and write some very minimal firmware. In effect, with appropriate external hardware your RPi could do this without any chip, but my guess is you want this as hard power-off in case the software on your Pi hangs, so I'll guess this is not an option.