"them that had gotten the victory over the beast":

Revelation 15:2 And I saw as it were a sea of glass mingled with fire: and them that had gotten the victory over the beast, and over his image, and over his mark, and over the number of his name, stand on the sea of glass, having the harps of God.

Is it possible that these, who are standing on the sea of glass mingled with fire, got their victory over the beast, as they were killed?

Those in the fifth seal, under the altar were told:

Revelation 6:9 ¶ And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:

 10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?

 11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.

They were slain for the word of God, and for the testimony which they held.

They were told that others would be killed as they were.

Could that be speaking about those in Revelation 15:2, shown above, and also in:

Revelation 7:14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.

and

Revelation 12:11 And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death.

and

Revelation 14:13 ¶ And I heard a voice from heaven saying unto me, Write, Blessed are the dead which die in the Lord from henceforth: Yea, saith the Spirit, that they may rest from their labours; and their works do follow them.

Could it be, victory through death?