Eleven's sister, Kali, did not escape Vecna in the Netflix series Stranger Things. She is not shown to have any encounters with Vecna in the series.
While Kali does have a connection to the Upside Down, her story focuses on her own personal journey of seeking revenge against the people who wronged her.
Kali's story is a separate plotline from Eleven's and Vecna's, and it remains unclear if she has ever encountered the creature or possesses any knowledge of his powers.
