Two types of Twitter voting are supported by M/IC.
Twitter Firehose based (formerly GNIP, now Powertrack v2)
Twitter Streaming API
Use of the Streaming API is free, but it does not guarantee that all relevant tweets are fetched. From open sources (rather than official docs) - via this interface we get approximately 1% of overall Twitter traffic. Therefore, if relevant Tweets account for less than 1% then we're likely to not lose any tweets. If more then we're likely to not count some Tweets as votes.
Firehose-based voting requires a commercial addition of Twitter firehose access, which your relationship manager can discuss.
Different types of tweets are supported by both methods:
Re-tweets - original text is used
Quoted tweets - comment text is used instead of original tweet, original tweet is discarded
Twitter hashtag voting must be enabled in the Project Settings before it can be used, as shown here
Then in your project, follow these steps to set up a social vote using Twitter Hashtag voting:
Create a new event, which you can start manually or on a timecode.
Create a Vote element within your event, with the same duration as the event, starting on a timecode at 00:00:00
Select Vote settings as required (one/many/max/min hashtags)
Add qualifying hashtags to question, e.g. #worldcupvot
Add option hashtags to answers, e.g. #redteam or #blueteam
Start the vote
Check results in the analytics tab