How do some people get so many followers ?

You can also get followers on twitter by using following tips:-
1.Get followers on Twitter with INTERESTING, RELEVANT CONTENT
2.Create a PROFILE that will get more followers.
3. FOLLOW people that you want to follow you.
4. INTERACT with the people you want to follow you.
5. All good things take TIME, including more Twitter Followers
6. EXCLUSIVE OFFERS for your Followers.
7. Attract New Followers with TWITTER COMPETITIONS.
8. 'LIVE TWEET' Events and TV Shows.
Thnx....

Yes It is right all the tips fallow the people then they fallow you

Even I wanted to increase the followers and traffic too. I am not able to get the traffic.

By using any tool or online too like twiends, they are providing free followers getting services.

If you want to increase your twitter follower just make your business page and try to follow only those people that are related to your page and tell your follower to share your page also then you easily increase your followers.