Can you disengage A320 autopilot with stick pressure?
Yes. I’m not sure of the amount of force, but from the A320 FCOM:


  AP DISENGAGEMENT
  
  AP1 or 2 disengages when: 
  
  
  The pilot presses the takeover pushbutton on the sidestick. 
  The pilot presses the corresponding AP pushbutton on the FCU.
  The pilot pushes on the sidestick harder than a certain threshold or moves on the rudder pedals above a threshold.
  The pilot moves the pitch trim wheel beyond a certain threshold.
  The other AP is engaged, except when localizer/glideslope modes are armed or engaged, or when the rollout or go-around mode is engaged.
  Both thrust levers are set above the MCT detent and the aircraft is on the ground.
  The aircraft reaches the MDA-50 feet (MDH-50 feet), or 400 feet AGL if no MDA/MDH, with APPR mode engaged and a non-lLS approach is
  selected.
  One of the engagement conditions is lost.
  
  
  Furthermore, in normal law with all protections available, the AP will disconnect if:
  
  
  High speed protection is active;
  Angle-of-attack protection is active (α prot + 1° is reached);
  Pitch attitude exceeds 25° up, or 13° down, or bank angle exceeds 45°;
  A rudder pedal deflection is more than 10° out of trim. 
  
  
  The standard way for the flight crew to disengage the AP is to press
  the takeover pushbutton on the sidestick. When the AP is OFF, the
  associated FCU pushbutton goes off. and "APl" (or AP2) disappears from
  the PFD’s FMA.
  
  *emphasis mine