In addition to optimizing your gig descriptions on Fiverr, as others have suggested, bringing traffic directly to your gig activity (not necessarily through SEO) can be helpful. The genius of gig sites is, it converts the promotion of each of your services into a landing page. By creating a url page for each of your gigs, you can treat each one like an affiliate landing page. You can therefore create a website (even a free blogger blog) to pre-sell each of your gig pages. You simply write a mini-post about the subject, and link to your Fiverr url.
You can also create a channel on YouTube to upload short videos on your gigs (that includes the fiverr urls in the video description), and embed each video to a post on your blog that talks about those exact gigs. Since digital marketing is an evergreen niche, you can now try to get a guest post published on every high traffic marketing site you can, with a link to your video, blog, or direct Fiverr page. This should make generating relevant traffic somewhat easy, without any further help from Fiverr.