The calendar cover art that Martin posted on Twitter is clearly marked as something inspired by the ASoIaF book series rather than something that is 100% going to appear on the show.
That said, the art is impressive and daunting enough that giant ice spiders such as this should definitely turn up.
Well, George R.R. Martin may not have finished Winds of Winter yet, but at least he has time to give a sneak peek of something that’s in the works for his A Song of Ice and Fire saga!