Complex sentence: Vincent had reportedly told his niece that he would be reborn as her son; according to the niece (as reported by Stevenson), Vincent told her: I hope I don't stutter then as much as I do now.
Split into simpler sentences: Vincent had reportedly told his niece that he would be reborn as her son. According to the niece (as reported by Stevenson), Vincent told her: I hope I don't stutter then as much as I do now.