Take the couch outside and remove all the cushions and pillows. Allow the couch to sit for several days to air out. Fresh air is one of the best cures for bad odors. If you cannot take the couch outside, open all your windows and use fans to propel air through the room to air out the couch.
Mix a mild liquid laundry detergent with water in a bucket and then use a sponge to completely wipe down the couch. Wiping down the couch with a mild detergent will help eliminate the odors. Use a clean sponge dipped only in water to wipe away the detergent. Allow the couch to air dry outside in sunlight for best results. Check any tags on your microfiber sofa for washing instructions before you wash the sofa. Water may alter the color of the sofa slightly.
Spraying the couch with a fabric freshener spray that is designed to cover or eliminate odors can help with the cigarette smoke smell. Make sure to spray the freshener into the cracks and crevices of the sofa. You may have to periodically reapply the fabric freshener to the sofa to help keep the smell at bay.
You may want to try other tricks to help eliminate the odor around the sofa. You can place activated charcoal around the sofa to help absorb the smell or use an ozone machine in the room with the sofa to help neutralize the odors. You can also sprinkle carpet deodorizer on the couch and then vacuum it off. Use plug-in air fresheners around the sofa to help conceal any remaining smells.