How can I become a digital influencer to serve my new startup?

Sarah is correct here.
Becoming an influencer or authority in any area takes time and dedication, is not something you can typically leverage over night.
My suggestions to you is stick to a hyper targeted niche, narrow down your vision and scale back all efforts to the most minimal most targeted effort possible that will yield you to the next effort all with one goal in mind.

In growth hacking, we take this approach as having minimal goals but approaching them aggressively to reach highest results at each goal level. No matter how minimal the goal might be feel, if you're moving closer to the bottom line the goal is worth the effort.

With that said once you have a niche and only focus on that the social platforms and users will begin to recognize this and turn to you.

A quick hack for boost, although it typically doesn't list is writing a piece for publication to local journalists or online blogger. Write about something in your niche, look for relatable blogs or journalists and send it to them. Follow the bloggers, message them, ask for guest articles, or make suggestions on their posts vi their comments with links to your own blog.

Dedicate a Facebook page with images (not info) and always include a link to that guest post, or your blog, or article.

For example, the first time I came out on television, I managed to get more views of the back stage images than I did on the actual show. I leverage that into more appearances and visitors to my websites and businesses. The authority level can after a lot of work tho. Expertise came to me in my field due to experience and education all I had to do is expose my insight but even that took time and consistency in one area.

Becoming an influencer, or even just gaining respect, within your industry takes time. Content marketing is a good approach, but you'll have to go into it knowing that it's a long-term strategy. Keep publishing content - start a blog so you can aggregate everything in one place. Do some research on what your audience and prospective customers need help with. What challenges do they face on a daily basis? What topics do they need to learn more about? What can you write that will be relevant and helpful to them?

As you continue to publish, keep promoting your pieces on social media. It may take a while to build up a bigger following there, but having great content will help you attract these folks.

You can also browse sites like Quora, Reddit, etc. and answer relevant questions - this is another great way to start establishing some credibility, and you might even be able to share a link to one of your blog posts if you do it in a helpful and non-spammy way.

I do happen to be an influencer / thought leader in my particular niche - with the network of colleagues and experience behind me that allows me to get meetings set - and I don't have many people reading my Posts on Medium.

My network, for the most part, doesn't read Medium -but I post there anyway just because it is another outlet for new people to find me on.

If you want people to take you seriously, you need to act the part.

I was recently at a very famous comedian's show, where he was testing new material. He was in a small room, not in the location he normally plays, and it was unannounced. Not everything was a hit (some was very funny), and he had a tape recorder to play it back later so he could further tweak.

As a professional, play to the smaller room when you don't have the spotlight so you can tweak your pitch and build that confidence. Then, when you call people, they will answer.

I helped a department in a big corporation to grow their twitter account from 95 (I) to over 2k in 18 months through organic growth. That's four years ago when twitter was not as popular today. I provided resources for our audience and monitored the response to adjust my content. It took persistent work.

For my personal tweeter account, I noticed that 400 seems like a tipping point. After a solid 400, it grew really beautifully.

You need to get out to meet your target market in person. Start a meetup group, attend networking events, and be a thought leader locally AND online. I'd love to hear more as I'd be happy to give you more tips on this.

You can get that done by treating marketing like an investment, not an expense, and hiring people who know what they are doing to grow your business.

Stop trying to do everything yourself. Stand on the shoulders of giants instead.