If it does get approved, then $300m would be invested, so 1.5% of the total value of BTC.
So there is about 35% chance of a 1.5% inflow, so the price should rise 0.5% on the basis of the ETF. Assuming it won't go down if the ETF is rejected...
1.5% inflow in ONE WEEK. The total value of Bitcoin took 7 years to accumulate. Now you are talking about 1.5% inflow in 0.2% of the time. This doesn't even take into account how many people will not be selling their coins just because they know that demand will be up.
As the infofront said, lets see what happens to the price when you try buying 300M worth of BTC in one week. The average amount traded is 30M per week, and that includes day traders that are buying and selling. This is 10 times that amount of pure buy pressure. I'm sure 10 times as many people will decided to just sell their coins at market price because the ETF just got approved
Not only that, that is only the first week. The ETF will be around longer than one week.