There are three things that are possibly going to occur if bitcoin ETF will be approved by the Securities and Exchange COmmission. The first is that bitcoin may increase in value because of the good news, 2nd is that bitcoins value will decrease in value or 3rd there will be no effect. So today what we have is only a possibility but we will see what will really happen only after it was approved.
There is only one thing that can happen.. The first one.. Because the investors will more assured to invest in bitcoin with minimal risk.. That's what will bring huge investment. And investment means increasing of demands. And demands make price increase