In my opinion humans are anchored on the physical plane and as such would not connect to the spiritual one enough to work as a living gateway themselves. You can communicate with spirits and summoning spells are common yet this is not the same as being a gateway yourself.
@ WInd, I have a friend who speaks of how she feel spirits passing through her often. She said she always feels chills and she does just randomly shiver, it can be nice and warm, and she'll shiver. She's been told by a psychic on the street she feels a lot of powerful energy flowing through her, and that she feels as though spirits pass through her a lot. It's a fun thing to think about.
@666Nope666 It is an interesting concept but by passing through her does she simply feel as if they literally pass through her vs exiting out of her as if she were a gateway? Having a non-corporal entity pass through your body is a different phenomenon than being some form of anchor/gateway for them. Some people can sense the presence of spirits typically referenced as clairsentience/clear feeling.
You can channel a spirit and the thoughts and feelings through your body. At times, channeling has been said to take on a possession type incident. Some incidences may be credible, I doubt some really occurred. If that is what you mean, yes it's possible, though I doubt all those that claim being able to do it, have actually done it.