"An author’s platform has long been something publishers look at — does she have a radio show, for example, or a regular guest spot on TV? But as local news outlets and book coverage have dwindled, the avenues for book publicity have shrunk, making an author’s ability to help get the word out more crucial. And when an author speaks to her followers about a book she wrote, she is talking to people who are at least a little bit interested in what she has to share.
" 'It’s become more and more important as the years went on,' said Marc Resnick, executive editor at St. Martin’s Press. 'We learned some hard lessons along the way, which is that a tweet or a post is not necessarily going to sell any books, if it’s not the right person with the right book and the right followers at the right time.'
"... Sometimes, publishing and marketing executives say, there is a mismatch between what people post about on social media and the subject of their books. Perhaps the books don’t provide anything beyond what they’ve already put on Instagram. It could be that the author hasn’t pushed the book to his followers effectively, or that those followers (the ones who aren’t bots, or paid for) aren’t terribly engaged with what he posts....
"In an effort to mitigate these issues, some book contracts now specify the number of posts required before and after a book is published....."
"A new dimension of this conversation is TikTok, which has become a powerful force in selling books. Successful “BookTok” titles are generally pushed by enthusiastic readers weeping into their camera phones about how much they loved the book, not authors shilling their own work. But book proposals by TikTok stars are now getting snapped up."
"Tanya McKinnon, a literary agent, said that it isn’t accurate to say that social media doesn’t matter for book sales. But the truth is that the industry doesn’t really know what it will do for any given book."