There are two confusing things.
The first one is whether to use the accusative or genitive in negations. It's a quite complex topic which has discussed several times here.
The second confusing thing is the word ничего itself. It's often misused instead of ничто in the nominative and accusative cases (just like чего instead of что). One can say for example "Ничего не вечно". It's similar to "It's me" and "It's I". While the latter is normal in modern English, the former is still considered wrong.