Nearly 40 percent of respondents said that they have purchased an item online after seeing it used by an influencer on Instagram, Twitter, Vine or YouTube, said the study conducted by Twitter and market analytics firm Annalect.

About 20 percent of respondents said they shared something they saw from an influencer while one-third of millennials (those born in two decades after 1980) reported that they follow a social media influencer on Twitter or Vine, reported.

Marketers are using social media influencers to build relationships with the people An  influencer can reach consumers via blogs and social networks that brands may not be able to.

Some time ago, "marketers would put household names on the front of cereal boxes," Jeffrey Graham, vice president of market research and insights at Twitter, was quoted as saying.  "Now, online influencers can sell other products to anyone with a smartphone," Graham added. For the results, the researchers surveyed more than 300 users to see how they responded toward brand influencers.

In the second part of the study, the team studied how 500 users exposed to display ads and other traditional digital formats compared with watching content from a social media influencer.The number of influencers from various walks of life had also dramatically increased on various social media platforms, the authors noted.

"This is telling us is that you don't have to be a mass media star or a household name to be influential and actually drive people to buy stuff," Graham noted.

According to Twitter-owned talent agency Niche, the number of social media influencers available to brands has grown from 6,000 to over 25,000 in a year.