The movie Ronin indeed takes inspiration from the graphic novel. They share core elements and themes, but the movie might have made some adaptations for the big screen.
In my opinion, Titanfall 2's story is great. It has a compelling narrative, excellent world-building, and it keeps you on the edge of your seat throughout.
It depends on your playing style. On average, you can expect to finish the Titanfall 2 story in about 7 hours. But if you take your time exploring and soaking in the details, it could be longer.