Contrary to previous answer, the iceberg didn't rip a hole in the ship's hull. It didn't even rip any hull plates off. However, the impact dented hull plates to pop enough rivets in enough compartments to sink it. According to computer models the total size of the openings (note the plural) was about 25 square feet, smaller than a single hull plate. Had it been a military ship, with the crew properly trained in damage control, they would have been able to contain the flooding.
The bow is one of the strongest parts of the ship, and the internal compartments were a lot smaller than amidships. Most likely, had the Titanic not tried to avoid collision, she would have most likely not only survived, but would have been able to limp into port under her own power. It would have been embarrassing for the White Star Line, but not nearly as tragic.
Today, the ships crews are trained, in case the collision is unavoidable, to avoid a glancing blow and hit the object head on.