Just one place and two points separate Southampton, in 18th, from the Hammers.
Austin scored a stoppage-time winner when the two sides last met in August and he is hoping to return from a three-month injury layoff to aid Saints at London Stadium.
"It’s massive," Austin told Southampton's official website. “We can’t look beyond the West Ham game – there’s no point.
"We’ve got to go into that game and we’ve got to win. Points are what’s needed now.
"Our season has boiled down to eight weeks, regardless of what’s gone on. It’s eight weeks now – that is it."