There are many social media campaign around. If you like, you can join them and earn money from tweet and retweet. Try to apply in one campaign to test and if you have experience already, you can apply upto 10 campaign at a time 
Ensure that you are aware about the rules and regulations of the campaign you joined. It should not happen that with same id you join multiple campaign and you are out from the campaign as they may have rule that only at a time you can support 1 campaign.
Yes at present making money from twitter is very much possible and with the price rising you can earn something for yourself.
This information he can get in the services section top which speaks about rules and regulations of joining in signature campaign. Even Twitter campaign has the same rules of joining in part of it.
Twitter is good to share the information about bitcoin or anything.
Twitter campaign is one of the ways to make money if you have a decent twitter account.
But not only that, if your followers are at a high quality , you can sell twits to large companies and you can get paid in bitcoins.
As long as your followers are real there is no limit for the money you can do from the followers.