I haven't been around a gas dryer in quite a while, but are you talking about the gas combustion flue vent or the dryer air/lint trap vent or both?
What is the btu rating of this dryer? You have to make sure the flue in the chimney is of a big enough size to handle the btu rating of the gas furnace, the gas water heater, and your gas dryer. Talk to your gas company cause the gas code has various tables for vent sizes depending upon the number of appliances and their btu rating. Have your friend write a will cause an overloaded gas flue will end up spewing combustion gas byproducts such as carbon monoxide into the home. Besides this may be an apartment. How would you like to be upstairs and the lower apartment doing something that might cause death for you and your family along with everyone else in the house. I can invision the headlines now.
Dryer lint is also a big cause of fire in homes. Just scroll down a ways to read about a dryer fire. Get someone licensed in the mechanical code such as a HVAC person to look it this before everyone in the house has to write their will and you face murder charges.