Some people believe that TV has had a positive influence on society. Do you agree?

Well, I think television has had a positive influence on society. Firstly because, it can help us learn some knowledge. For example, Discovery Channel, National Geographic, and History Channel are all very good TV programs. These programs popularize science and knowledge among TV viewers. Secondly because, watching TV is a good way to have fun and release pressure of work and study. Family members and friends can watch TV series together, such as Prison Break, Big Bang Theory, and Gossip Girl. They can chat about the plot and characters. So in this way, the relationship has been enhanced among family members and friends.

If possible, please help me with my pronunciation too. Thank you!

Firstly, because it can help us enhance/widen/broaden our knowledge (any of the 3 words would be more natural).  You obtain knowledge or learn things.  

Secondly, because watching TV is a good way to have fun and release the pressures created by work and study.

can watch TV series together....  can watch some/many/a TV series together

All in all it's very good and would pass with flying colors most anywhere.  Excellent English!