In addition to what was noted in the answer above, pitch may also refer to a sales pitch, which is a persuasive talk or presentation that aims to motivate a person or company to purchase a product or service. This can be an elevator pitch, a short, pithy persuasive talk that sums up the importance of a product or service in however much time (usually less than a minute) that it takes a person to ride an elevator to his destination. This version of pitch dates to 1943 and may derive from the idea of pitching or throwing a baseball. This could also refer back to pitch's 1847 definition of "to work vigorously."
The word, going back to the 1200s, can also mean to set something up or fasten it in place, hence the origin of the term we still use, pitch a tent.