There are many ways to identify the influencers. A few quick ways are looking at the KLOUT score. Klout is a mechanism which generates a score based on fans/followers and engagement levels on different social channels. Apart from the followers base, you can also go deeper into it and look at the followers’ nature, how many quality followers do they have etc. There are other factors which can be taken into account such as the traffic on blog, subscribers and niche topics relevant to your desired interest.