Being a good influencer is all about trust and engagement. People trust influencers because they have similar interests and views to their followers. Having fake followers is wasting everyones time. Engagement is equally important, because it is only when people are actually seeing and reading the posts that they will they be affective. This can be measured by engagement rates. Indicators such as the number of 'likes' and comments.
The next critical factor is relevance. Targeting the people by theme and location. This is espcially true in the vegan market.