When it comes to PvP, more players always makes it easier. Sometimes, that's not a good thing, like when you're specifically trying to fight outnumbered to stretch yourself. But in some situations and against some enemies, it's prudent and useful.
While most people offer the advice to join a player-run corporation so you have a group of people to talk to in game, that advice is usually offered more to ensure long-term engagement than to occupy each play session. The simple fact is, joining a corporation isn't enough. Nor is it enough to have a certain corp size.
The real factor you should be looking for is how many mains your corp has in the same place.