The following is a little fuller context with the passage you quoted:
Revelation 14:9-12 (CLV) . . .
9 And another, a third messenger, follows them, saying with a loud voice, "If anyone is worshiping the wild beast and its image, and is getting an emblem on his forehead or on his hand,
10 he, also, is drinking of the wine of the fury of God, blended undiluted in the cup of His indignation, and he shall be tormented in fire and sulphur in the sight of the holy messengers and in the sight of the Lambkin.
11 And the fumes of their torment are ascending for the eons of the eons. And they are having no rest day and night, those worshiping the wild beast and its image, and if anyone is getting the emblem of its name.
12 Here is the endurance of the saints, who are keeping the precepts of God and the faith of Jesus."
It only says the smoke from their torment is ascending for however long. It does NOT say their torment is for however long. If I smoked a cigarette in my dad's car, the cigarette would only burn a couple of minutes, but he'd say he could smell it forever. The fumes from burning something can be quite impossible to remove from things like clothes. While it seems not having rest is limited to for as long as they are worshipping the wild beast and its image. Anyway, since it is day and night it can only be as long as the earth exists and the Bible says it and everything in it will dissolve with a fervent heat:
1 Peter 3:10-13 (CLV) . . .
10 Now the day of the Lord will be arriving as a thief, in which the heavens shall be passing by with a booming noise, yet the elements shall be dissolved by combustion, and the earth and the works in it shall be found.
11 At these all, then, dissolving, to what manner of men must you belong in holy behavior and devoutness,
12 hoping for and hurrying the presence of God's day, because of which the heavens, being on fire, will be dissolved, and the elements decompose by combustion!
13 Yet we, according to His promises, are hoping for new heavens and a new earth, in which righteousness is dwelling.
Getting them to show any verse that says what they say, "Conscious continuous torture for ever" is impossible. I can't find it. Even concerning the goat nations in Matthew 25, in verse 41 it is the fire that is eonian, or as KJV has it, "Everlasting fire," NOT the torture. If that was the point we were supposed to get it would exactly say so. In verse 46, while actually referring to their "chastening eonian," (CLV) a point good lexicons reveal, the KJV has, "everlasting punishment," which if continuous would read, "Punishing." If they want that one word verified from the orginal then, tit for tat, the adjective form of "eon" (an age) may be insisted on. There are a minimum of five eons, before and after them, and they all end, individually and collectively.
There are only 2 or three places it even comes close, yet Scripture never does actually say in its own words that there are any humans undergoing "conscious continuous torture for ever." Here's an example of when it speaks several places of "Whosoever was not found written in the book of life was cast into the lake of fire" (Rev 20:15, KJV) that "whosoever" in Greek is "If" and there is no answer whether or not there were any "whosoevers" found by that time. The "if" is not answered. Notice too, duration of suffering is not address in the preceding verse.
When the facts are pointed out to them it's good to also warn them of adding to the words in the Unveiling, the Revelation, the Apocalypse:
Revelation 22:18-19 (CLV) . . .
18 "I am testifying to everyone who is hearing the words of the prophecy of this scroll: If ever anyone may be appending to them, God shall be appending to him the calamities written in this scroll.
19 And if ever anyone should be eliminating from the words of the scroll of this prophecy, God shall be eliminating his part from the log of life, and out of the holy city, that is written in this scroll.