The two witnesses are indeed two men, who are martyred ...

Revelation 11:3-4 And I will give power unto my two witnesses ("martus" in the original Greek, meaning witness or martyr), and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth. These are the two olive trees, and the two candlesticks standing before the God of the earth.

Their identities were revealed by the prophecy of Peter ...

Matthew 17:4 Then answered Peter, and said unto Jesus, Lord, it is good for us to be here: if thou wilt, let us make here three tabernacles; one for thee, and one for Moses, and one for Elias.

Mark 9:5 And Peter answered and said to Jesus, Master, it is good for us to be here: and let us make three tabernacles; one for thee, and one for Moses, and one for Elias.

Luke 9:33 And it came to pass, as they departed from him, Peter said unto Jesus, Master, it is good for us to be here: and let us make three tabernacles; one for thee, and one for Moses, and one for Elias: not knowing what he said.

A "tabernacle" is a body of flesh. Peter (unknowingly, through the Holy Ghost) prophesied bodies of flesh for the spiritual Moses and Elijah that he saw - indicating that they would be as men at some time in the future, just as Jesus was in a body of flesh.

2 Corinthians 5:1 For we know that if our earthly house of this tabernacle were dissolved, we have a building of God, an house not made with hands, eternal in the heavens.

2 Peter 1:13-14 Yea, I think it meet, as long as I am in this tabernacle, to stir you up by putting you in remembrance;  Knowing that shortly I must put off this my tabernacle (i.e. Peter was prophesied by the Lord, to be killed in the flesh), even as our Lord Jesus Christ hath shewed me.

The witnesses were alive at the time of Hitler's Jewish Holocast - by killing millions of Jews, he was actually targetting the 2 witnesses, just like during the time of Jesus that Herod had many children killed whilst he was trying to kill Jesus.

in Jesus' Name,
Lester