Google does count social signals like tweets and likes, etc. But I would doubt it if the number of followers in your profile page would make any impact on the page's SEO score.

Also regarding building links to your other account, well that certainly should build up more authority to the page; however I believe that most of the authority will be coming from Steemit.com's domain itself so don't worry too much about optimizing the profile page itself; otherwise I would work on a single article / post page and optimize/work on it for the target keywords.

With that being said, I don't believe fiverr gigs would be of much help as most of the links you'd get from gigs would be spammy; unless you're paying top dollar for higher quality gigs.