John Gill Commentary Revelation 7:8

"Of the tribe of Zebulun twelve thousand; Of the tribe of Joseph twelve thousand; Of the tribe of Benjamin [were] sealed twelve thousand." — Revelation 7:8 (ASV)

Of the tribe of Zabulon [were] sealed twelve thousand
Which signifies "dwelling", (Genesis 30:20) ; and was the tribe in which Christ has his dwelling, and where he much conversed; and may denote his gracious inhabitation, as well as that of God the Father, md of the Spirit, among the saints and sealed ones.

Of the tribe of Joseph [were] sealed twelve thousand ;
whose name signifies "adding", (Genesis 30:24) ; and may intend the additions both of numbers, and of gifts and graces to the churches of those times.

Of the tribe of Benjamin [were] sealed twelve thousand ;
this word signifies "the Son of the right hand", (Genesis 35:18) ; showing, that these sealed ones are as a signet on God's right hand, and are as near and dear unto him as a man's right hand is to him; see (Psalms 80:17) . Now twelve thousand out of each tribe make just the number of a hundred forty and four thousand, (Revelation 7:4) ;

The tribe of Dan is not mentioned, it may be because of the apostasy of that tribe, one of Jeroboam's golden calves being set up there; showing that God had no sealed ones of that sort, and instead of him Levi is reckoned; though that tribe had no part in the division of the land of Israel, yet had a part in Christ, and is therefore mentioned in this mystical account. Nor is the name of Ephraim used, it may be for the same reason; there having been a great defection in that tribe from the pure worship of God, and instead of him the name of Joseph appears.