@Thib @gargron @kaniini First off, is it using anyOf? The polls I've seen implemented seem like they should use oneOf, not anyOf: https://www.w3.org/TR/activitystreams-vocabulary/#dfn-oneof
As for what property to show for the number of voters, I'm not sure, it doesn't look like a good one is defined in AS2... it should probably be a new property.