You write a blog post about your infographic generator, and included a link to the tool in the post so people can try it for themselves. Let's say the visitor-to-lead conversion rate is the same on this blog post as it was in your PPC campaign -- 2%. That means if 100 people read that blog post in your first month, you'd get two leads from it. But your work is done now. And over time, that one blog post you wrote years ago will continue to generate leads over, and over, and over, every single month. And not just that blog post -- every blog post you write will do the same.
With a marketing team size of around 18, your content marketing team will be staffed with all the same roles -- bloggers, long-form content creators, SEO specialists, designers -- just multiplied. Aim to have three bloggers on staff, and two employees for each of the other roles. It's wise to have one of those bloggers have expertise in editing, too, so there's someone dedicated to maintaining content quality as output increases.