Firstly, social media followers/friends, even if organic, are only indicative of general popularity.
You cannot lift the overall following of someone over social media and apply that to anything meaningful because people act in the moment over social media. If someone or something has a million Twitter followers for example, you cannot apply that to mean a million potential buyers.
Marketing companies use social listening platforms to scope how audiences engage with products, people and other things. A social listening platform looks at how people engage with things and in what way (that's all put through proven algorithms to give back a tangible measure).
Buying followers over Twitter, it's done but it's not *that* useful as it isn't a real audience; it can just help to give an illusion of popularity which will encourage others to follow. Savvy marketing companies use influencers, which is where they identify people or businesses that have a strong, relevant following themselves and have some kind of interest in the brand/person/thing and encourage them to influence their following to pay attention.
A good XF example would be 1D endorsing a contestant or a product that was relevant to both themselves and their audience; the audience will then pay attention and potentially buy into the thing that's being sold.
Or a magazine / paper / website focusing on a particular thing or talking positively about it.
So, to answer your question, it is highly unlikely that any contestants Twitter followers are "bought", that's an over egged thing; although it happens, however it is quite possible that they have been boosted through influencers in fact I'd expect it.
