I wouldn't say they increase the chance of getting hired directly, but the skills, endorsements and recommendations will all increase your chances of a recruiter finding and contacting you, so it's a good idea to leverage them. It's really just SEO, you have to have the keywords on your profile if you want to show up when recruiters are looking for people with those skills.

Here's a few other tips that might be helpful: https://www.linkedin.com/pulse/20140320151331-142790335-11-s...