Thunder Cage is a move that is has a base power of 80. After the move is used, the enemy can't switch out from non-pivoting moves. The target affected takes 12% damage every turn for 4-5 turns due to the trapping effect.
So if you were asking about if the trap effect deals base 80 damage every turn, then no, but if you meant that Thunder Cage's power doesn't change every turn, then yes.