The FS Traffic fleet is all set up with the correct airline ICAO/IATA codes in their config files, so that if airline codes have been assigned to specific gates at airports by the scenery developer, the aircraft will generate at the same gates as they would in the real world.
The main limitations of this are that it does require airline codes to be assigned to gates by the scenery developer, and they must also be set up correctly. Typically, they are set up correctly on payware third-party airports, but the default, auto-generated MSFS airports likely won't have airline codes set up, so the aircraft will generate wherever there is a free gate/parking position that can accommodate that aircraft type.
Hope that helps.
Mark - Just Flight