Apologies for the late response, I've been busy holidaying it up
I wasn't sure how familiar people were with the content marketing term around here, so I gave some real-life IT examples that people would recognize. I wasn't trying to suggest that OP should try to emulate them outright, sorry for the confusion!
I figured it would be worth sharing the most popular trend in SEO that I'm aware of as a way to help focus OP's research and see if they thought it could work for them... With that said, please don't invest effort and/or money on building a whole new branch of marketing just because a guy on the internet said it might help
Scott's definitely right that SEO by itself isn't going to be a magical panacea for drawing a bunch of customers in, and there is always a good chance that hiring a dedicated SEO "expert" could end up being a bust. Passive traffic is helpful but it's not the constant flow of paying customers that some make it out to be.
I think the reason why SEO is usually considered an essential part of online marketing by most marketers I follow is because putting current SEO best practices in place doesn't just generate passive traffic. Since most current recommendations focus on making your site experience easy to use and helpful for visitors, having SEO in place means the people drawn in from your ads elsewhere will be more likely to stick around and explore. It also means you have some reliable way of tracking where site traffic is coming from, so you can track which ads you're putting out are actually bringing in traffic.
With content marketing specifically, it means your ads on social media can have a more interesting hook than a small discount or just a link to your site - Even if no one ever googles "fleece vs down jacket insulation", you could have an ad that points to the imaginary article mentioned in my last post that gets shown to people who list camping, hiking, hunting etc as an interest on FB. Then, even if they weren't actively searching for that info, their interest might be piqued by the article and either way you've gotten the idea that you're an authority on that sort of thing out to them. I'm pretty sure this is how Dollar Shave Club gets quite a few new customers - I never googled "subscription razor blades" but I get reminded of their existence every few days!
I would say that no one here can know enough details about the business in question to give a truly definitive answer for you because some of the details needed to form that answer (current sales volume, average customer lifetime spend, etc) would be foolish to post publically.
Ultimately, if you are committed to expanding the digital sales side of your business, you should consult with someone who specializes in digital marketing and discuss the details of your business, including what you do to market yourself right now. They they can help you build a digital marketing plan with clear goals, documented methods for achieving them, and metrics that you can use to measure the ROI on each method. Otherwise, it's all too easy to spend money trying out a smattering of different methods without ever really knowing which, if any, actually helped.