Final answer:
The use of figurative language most significantly shapes an author's poetic voice by creating vivid imagery and connecting emotionally with the reader.
Step-by-step explanation:
The stylistic element that most contribute to the author's poetic voice is the use of figurative language to create vivid imagery. This technique not only paints a picture for the reader but also evokes emotions and connects deeper with the audience through metaphor, simile, personification, and other figures of speech. While sentence structure, like the use of fragments and punctuation, can certainly shape the narrative and influence pacing and tone, it is the use of figurative language that most distinctively captures and conveys the author's unique voice within poetry.