Oh, novelists, I'm sorry to be the bearer of bad news (although I'll remind you not to shoot the messenger), but you should take a look at your platform, just like those nonfiction writers.
Is platform in any way essential to fiction the way it is to non? NO. I'll be clear on that. Fiction is sold on the story and the writing. And the economic viability. :) Platform, for novelists, is a bonus. (Nonfiction writers, see yesterday's post stat).
So if a nonfiction "Platform" means convincing editors and agents 1. why you're the best person to write a book and 2. that there's a large audience already eager to read on the subject, what does platform mean for novelists? Answers would be 1. because I thought of it first and 2. Um...everyone wants this! Of course!
And those answers aren't helpful. Platform, for fiction writers, is more about demonstrating that there are people out there who like you. Who think you're funny, say. Or people who find you engaging. Check out Chuck Wendig and Maureen Johnson on Twitter for examples of people who do this really well. Copy them. (sort of serious)
Fiction queries are 100% focused on the novel: who's the main character, what's the big choice they're facing (See Query Shark if you're at all unclear on what a query should do). You don't have to mention your 2K Twitter or blog followers in your query.
But agents will Google you. They will find your 2K Twitter followers and your popular blog (in email queries, at the bottom where you write your contact info, you can include these links, too). They, and the editors to which they pitch your book, will be impressed that you've gone out there and started talking with what will become your audience.