It depends on how you are looking at the stars. Modern astronomers have well defined boundaries for each constellation. That's because there are lots of lights where I am, and the sky gets washed out. But that's only with your naked eye.
Time exposures using cameras also can show much fainter stars.
If you look at any basic astronomy textbook I'm sure you'll find some long exposures of Orion. Stars can even be so faint you need a telescope to see them, and the bigger the telescope, the fainter you can go. Using the biggest telescopes in the world, I am sure you can see many millions of stars inside Orion's borders. And finally, there are lots of other galaxies, extremely faint, in Orion, each containing many billions of stars. It just depends on how faint you want to go.