With Gad we see recovery. After the apostasy of Dan, Gad came in to recover the lost victory (Genesis 49:19). The victory of Judah, the lion, had been lost by Dan’s apostasy, but Gad regained it and even enlarged it. Gad is not a young lion but a lioness producing cubs. He is the continuation of the victorious Judah and Dan.
God was so happy about Gad’s recovery of the victory that He enlarged him [Deuteronomy 33:20]….Gad was enlarged not only by God, but also for God. He was enlarged for the executing of God’s righteousness among God’s people.
The best aspect of Gad is not merely that he crushed the enemy’s head but that he would not enjoy his victory by himself. Although he gained land on the east of the Jordan, he would not enjoy it until the other tribes had won their portion of the land. Gad went with the other tribes to fight the battle to gain more land so that all the tribes might be able to have their share. The New Testament interpretation of this Old Testament figure is that we must always take care of the brothers, the members of the Body. (Witness Lee, Life-Study of Genesis, ch. 103)
Further reading: the recovery with Gad.