How is Moksha directly shown in Lord Krishna's stories of Bhagavad Gita?
The idea of "moksha" or liberation from one's cycle of pain in consciousness can be seen in the idea of surrender to Krishna. This is probably best seen in the Gita when Arjuna wonders how to balance the pain intrinsic in one's duty. Moksha is present when Arjuna learns to place his trust in Krishna, and surrender under to him. All pain and agony disappears when Arjuna learns that the submission to Krishna is where moksha is evident and where pain disappears.
The concept of Moksha in Lord Krishna's stories revolve around this particular element. For those who end up trusting in Lord Krishna, their suffering ends and a sense of moksha or liberation is evident. For example, when Draupadi calls out to Krishna, she is saved by him, her suffering ends. It is presumed that she would gain moksha because of her ardent devotion to him. Even Krishna himself achieves moksha at the end of his life as he ascends to heaven once he is inadvertently attacked by a hunter. In the mythology of Krishna, moksha is present when one recognizes that Krishna is the ultimate reality. There can be no real determination of "instant" moksha, but it certainly seems that all of the Krishna narratives argue that if one seeks moksha, it has to reside with a fervent devotion to Krishna.