Yes, Jake Gyllenhall is a Jew. Gyllenhaal is known for his roles in October Sky, Donnie Darko, The Good Girl, Brokeback Mountain and Love and Other Drugs.
Gyllenhaal was born in Los Angeles. His parents are film director Stephen Gyllenhaal and film producer and screenwriter Naomi Foner. Maggie Gyllenhaal is his older sister and is also an actress. Gyllenhaal's father is of Swedish and English descent. His mother is from a Jewish family from New York City, and Gyllenhaal has said that he considers himself "more Jewish than anything else."
Gyllenhaal is politically active. He shot a commercial for Rock the Vote during the 2004 presidential election and he also campaigned for Democratic Presidential candidate John Kerry. He has also spoken out against climate change and participated in a campaign for the American Civil Liberties Union.