I'm not one to ponder the existence of such a thing, at least not in a spiritual sense. As a self identified atheist, I don't find that its terribly useful to speculate about a concept so deeply linked with religions and higher powers and the after life, which I find to be destructive - more than noble - ideas.
I don't believe that our consciousness, the base of what makes us who we are and behave or think the way we do, will continue to exist beyond our death. Its through biological processes that we are able to think, or even feel the way we do, and after the brain no longer functions, neither do we (whatever we are).
However, this is not to say that our consciousness does not benefit greatly, at least for some of us, when we write. When I sit down and put words to my ideas or feelings, my awareness is heightened. My consciousness is soothed, or at least nourished, when I am able to transmit my ideas from my body to a place outside of me. And when others read it and understand, the thinking me is validated.
If the work I write continues to be valued after my body dies, this will be the closest to a soul I'll ever possess. If not, if it only benefits me in the finite time I spend on earth, I'll be pleased. I'm just a speck in the grand scheme of things anyhow.