Revelation 19:3

See commentary on Revelation 19:1.

Her smoke rises up
Rises up is ἀναβαίνει [anabainei] , present tense: it presently rises. The same verb tense appears in Revelation Rev. 14:10+ which describes the ongoing torment of the Beast worshipers in the Lake of Fire: “And the smoke of their torment [presently] ascends forever and ever” (Rev. Rev. 14:11+a). Like the torment of the Beast worshipers, the smoke of Babylon’s destruction continually rises to emphasize the ongoing reality of her destruction.

forever and ever!
εἰς τοὺς αἰῶνας τῶν αἰώνων [eis tous aiōnas tōn aiōnōn] : into the ages of the ages. From the time of her destruction and throughout the Millennial Kingdom, the area which was once Babylon will be burning pitch and a prison for demons (Rev. Rev. 18:2+). The text implies that her destruction is so permanent that the land itself will be continually dangerous and unavailable to humans:

Its streams shall be turned into pitch, and its dust into brimstone; its land shall become burning pitch. It shall not be quenched night or day; its smoke shall ascend forever. From generation to generation it shall lie waste; no one shall pass through it forever and ever. (Isa. Isa. 34:9-10)

Forever and ever has several aspects: (1) the destruction of the city is permanent—it will never be found again; (2) those destroyed in her will suffer eternally in the Lake of Fire; (3) the area occupied by the city will continually burn until the new heavens and the new earth, when the first earth passes away (Rev. Rev. 21:1+). See The Destruction of Babylon.