William Branham and the Watchtower Society
William Branham borrowed a number of doctrines from the Jehovah's Witnesses (aka the Watchtower Society). These include:
William Branham refused to speak against the Watchtower Society
In 1954, William Branham was asked the question - Is Jehovah Witness a false sect? It is interesting that he would not answer the question:
Did he refuse to respond because he had studied many of their doctrines and was incorporating many of them into his teaching, including the belief in a "seventh" messenger?
William Branham considered Jehovah's Witnesses to be Christians
I said, "If he can't be there, I can't either." That's right. I said, "If we're interdenominational, that means everybody; I don't care who it is. If it's Methodist, Baptist, Jehovah Witness, whatever it is, they're going to be there just the same. And we can't draw straws, and say this fellow has no right, because we're perfectly brethren together, and that's the way we want it to remain that way." So no matter what church they go to, they're… We're all brothers in Christ, and that's when we're born again of the Spirit. And I appreciate Brother Joseph with all my heart.
William Branham studied Jehovah's Witness doctrine
I'm going to call the attention to one denominational church, the first church that ever spoke to me about Jesus Christ when I was a sinner, the Seventh Day Adventist. The Seventh Day Adventist said the seal of God is His sabbath, because a seal shows a finished work, that He's been sealed in the Sabbath. And keeping the Sabbath day is a memorial that you're sealed. Now, you Adventist know that, you know Dr. Smith, and the Home Bible Circle Readings and all that. I have them all in my study, and all of Jehovah Witnesses and so forth like that. Where—whenever they raise up, I know their points. See? I know where they're going to. So now, Sabbath day is not a seal. A Sabbath day was a seal of God's creation. He finished it then and sealed it (That's right.) with His Sabbath. But it was a type of the Christian Sabbath.
The seven church ages
Charles Taze Russell authored a book entitled "The Finished Mystery: A Helping Hand for Bible Students" which was published posthumously by the Watchtower Society in 1918.
In it, Russell describes his "revelation of the seven church ages" with the first messenger being St. Paul and the last messenger (to the Laodicean church) being Charles Taze Russell as noted on his gravestone. Russell was the first one to assign names to the seven angels of Revelation 2 and 3.
Russell, like William Branham, believed that he was chosen for his "great work" from before his birth.
The November 1, 1917, Watch Tower, carried an article titled “A Tribute to the Seventh Messenger” in which it said:
Given that William Branham studied the publications of the Watchtower Society, it is likely that this is where he got his idea of the "seventh church age messenger".