I'm pretty sure that polls like that are ineffective for discerning the impact of any type of marketing. The best evidence I can think of for whether somebody found something influential is whether they liked or re-shared a post, and there's plenty of evidence for that. Those are, after all, the sorts of metrics typically used for measuring the success of a social media campaign: https://www.socialmediaexaminer.com/10-metrics-to-track-for-...