Component contributions to “sound stage”

Very good question...

I would say speaker placement (back wall, rear wall, toe in/out) seating position are probably the most important. Of course, recordings and components all contribute to soundstage.

The recording.

All your components and the recording.

@mazian  +++
The soundstage is created by the RECORDING ENGINEER when the recording is being MIXED.  If it’s not recorded onto the source recording in the sources, digital source nowadays, no equipment  ie. media playback equipment, at any cost, will create one in your room. 
YES. Speaker placement in the room is very important. Toe in, distance from sidewall and back wall, and ceilings, acoustics treatment, all play, a role in creating a soundstage. if you don’t get it right, you won’t get a soundstage.
Again…No matter what, you won’t get a soundstage, if it’s not on the source media!  
There was a thread just a couple of days ago that reviewed this topicl.
Bent

@elliottbnewcombjr , I totally agree with you!

Just a quick observation from me. After not having changed a component in almost a year, I took a leap and spent close to 4k on a new vacuum tube preamp with self generating power. I could not believe the enhanced separation and much improved sound stage. So, for me at least, my preamp upgrade made a big difference with regards to the OP's question.