No one really knows, but it's very reasonable to assume that there is a link. However, the link might not be as strong as many employers would like to believe.
If there are two programmers who are equally good, but one knows Java and the other knows C++, Google would hire both. Really.
You certainly don't have to inform your manager. Most people don't, so you wouldn't be doing anything unethical or even out of the ordinary. In fact, most people inform their manager only after they've received and accepted another offer.