Interesting indeed , I wonder how representative the sample is
yeah a big number, but not necessarily representative of the population.
I don't know what news.com.au is but it's likely to have a certain demographic, especially in this day and age when people have lots of options for news. But they have to at least be news readers. Then out of the subset of people who are news readers, and a sub subset of them whom read news.com.au, there will be another sub sub subset who are interested in doing the survey - those are likely to be the ones who care about the issue the most, on either side.
News.com.au sounds like a pretty normal site, so probably doesn't attract the progressive audience that would be anti Folau