I have 14k followers on my main Twitter account, and I usually notice a slight uptick in followers whenever i share a new Steemit post. Maybe test different hastags to increase exposure? I also include my Steemit link in my Twitter Bio.
When I write, I keep Google in mind. I'm here for the long haul, so by adding a touch of SEO, my aim is to draw new users to Steemit through search, long after the payout window closes.