What Arafat rejected was tiny bantustans surrounded by apartheid, Jewish only settlement blocs and apartheid, Jewish only roads (separating the bantustans, one from another). That 90 percent figure might represent the actual percentage of area that would be called Palestine, but only about 40 percent of that would actually be controlled by the Palestinians, and that 40 percent would be in the form of tiny areas separated from each other by the settlements and the roads.
It would not have been possible to have a viable state in the area that was being offered to the Palestinians.
Here is what Israel was offering the Palestinians...
The Israeli map shows that Israel has no intention of ever letting the Palestinians have a viable independent state. They will only consider giving them enough to be able to say that they "gave the Palestinians a state", but not enough for the Palestinians to be able to live and prosper.