This animal, with its huge and massive stature and primitive behavior primarily stands for one's 'animal', untamed aspects of personality which most of the times are repressed in the subconscious, but cannot always be directed and controlled by reason. Most wild animals which populate people's dreams stand for primitive desire, including sexual ones, and instincts which sometimes are hard to repress and 'tame'.
Consequently, if the gorilla in your dream is aggressive or rebellious this means that desires in your subconscious want to break the 'surface' and get out of control, no longer to be managed by the intellect.
On the other hand, if in your dream you succeed in dominating the big animal or even kill it, this means that you are going to successfully repress your inmost instincts and desires and keep a balance between the 'beast' inside and the unwritten moral values imposed by the society and education on any individual.
Gorilla also signifies brutality, therefore our brutal way of dealing with problems and discussing with people or the others' brutality in their relationship with us.