As of today around 3pm Pacific, they've announced they're still going forward with it: https://www.sxsw.com/covid-19-attendee-information/

> Regarding the current Coronavirus (COVID-19) outbreak: SXSW is working closely on a daily basis with local, state, and federal agencies to plan for a safe event. As a result of this dialogue and the recommendations of Austin Public Health, we are proceeding with the 2020 event with the health and safety of our attendees, staff, and volunteers as our top priority.