I believe that ethereum is not depending on bitcoin. Because back on febuary the price of bitcoin is stable while ethereum pump to the moon and reach1.4k usd. They have different market so they are different but its true that bitcoin price influence altcoin price.. but not all the time
Yes, you have a point, we could not easy to say that both coins are connected but as what I have notice altcoins are swinging when bitcoin price moved either downtrend or in bullish price. Actually, that does not depend on the price of bitcoin, ethereum price swinging and effect because of the price movement on bitcoin but not all the time I guess. Who knows? No buddy knows if they are connected.