New York’s Ensemble Studio Theatre is surviving the suicide of founder Curt Dempster, its guiding light. “Before his suicide in January, Mr. Dempster, 71, was fretting that his theater, perpetually on the brink of fiscal crisis, would have to cancel its pièce de résistance, the annual marathon of one-act plays. Piling his sudden death onto this precarious existence might have made it seem that the end was nigh for the theater. But that has not happened.”