officially for counsel or often to exercise authority and rule (Dan. ii. 49; Jer. xvii. 19; xxxviii. 7).
The promise that Abraham's seed should possess the gate of his enemies is idiomatic figurative language, equivalent to saying that they shall be victorious over their enemies, and take possession of their cities. This was fulfilled when at the conquest of Canaan the Israelites took possession of the land and thus assumed the position of lordship over the doomed nations who are spoken of as their "enemies."
We may notice, by way of contrast, that in Jer. i. 14–16 God threatens that as a punishment on Israel for their sin He would call all the families of the kingdoms of the north, and "they shall set every one his throne at the entrance of the gates of Jerusalem," which is equivalent to saying that the Gentiles would possess "the gate" of Israel—which as a matter of fact, they are now permitted to do by treading down Jerusalem and scattering the people until the times of the Gentiles are fulfilled.
