There is A LOT of symbolism in this chapter of Revelation. Anyone who attempts to literalize this too much will surely end up stuck in a muddy mess they cannot get out of. But is there anything in the chapter that can prove that this is already fulfilled? Well, yes, yes there is.
I won't go to far into detail on the first 2 verses because that's not the point of this one but in the first 2 verses of the chapter we can see that this is clearly speaking of the destruction of Jerusalem at the end of the age. The temple is CLEARLY still standing in verse 1 which clearly shows this book was penned before 70ad. Also, we see that this temple was going to be given over to the Gentiles to be trampled under foot for a period of 42 months. Now, if you want to argue that irrefutable point then Lord help you. But let's continue towards the end of the chapter. It reads...
"Then the seventh angel sounded: And there were loud voices in heaven, saying, “The kingdoms of this world have become the kingdoms of our Lord and of His Christ, and He shall reign forever and ever!” And the twenty-four elders who sat before God on their thrones fell on their faces and worshiped God, saying:
We give You thanks, O Lord God Almighty, The One who is and who was and who is to come, Because You have taken Your great power and reigned. The nations were angry, and Your wrath has come, AND THE TIME OF THE DEAD, THAT THEY SHOULD BE JUDGED, And that You should REWARD Your servants the prophets and the saints, And those who fear Your name, small and great, And should destroy those who destroy the earth." Rev 11:15-19
Now, clearly at the time of the 7th trumpet when the Kingdoms of the world become the Kingdoms of the Lord, we see something else mentioned. It would be at this time that the dead would be raised for judgment and also for reward. Well, again, let's get this wild symbolism back in context. What did Jesus say?
"For the Son of Man will come in the glory of His Father with His angels, and then He will REWARD each according to his works. “Assuredly, I say to you, there are some STANDING HERE who shall not taste death till they see the Son of Man coming in His kingdom.” Matt 16:27-28
So Jesus already told us that the judgement and the rewarding according to works would occur before those men standing there died. We also know from numerous other texts this is true like Daniel chapter 12 when the resurrection and judgement was assured to be finished at the 42 month destruction of the holy people.
Therefore, you can play with the meaning of the 2 witnesses and the 7th trump and all of that symbolic language all you want. This picture in Rev chapter 11 was fulfilled at the destruction of Jerusalem at the end of the age.