Yes a ceiling fan will help keep the mosquitos away and here is why.
According to RAID.com "Mosquitoes pick up on a variety of cues to find their victims—from the carbon dioxide you emit when you breathe to the odors you release in your sweat."
Ceiling fans provide many benefits on a patio. A ceiling fan provides a cool breeze that makes the temperature feel lower. As well as making your patio time more enjoyable, this also reduces the amount of sweat you release. In turn this will also reduce the amount of mosquitos that you attract.
Breathing is something we all can not do without. However the air movement of a ceiling fan on the patio will dissipate the carbon dioxide that we exhale. This will also reduce the number of mosquitos that you are bringing to the party.
Lastly, mosquitoes are not great at flying. They fly at slower speeds and a little airflow around your patio is an excellent way to deter them from being the annoying guests.
Have a great time on your patio!