As I see to coin market cap, yes the increase of bitcoin leads to increase in all alt coins,

• But the ratio of increase in bit coin is smaller comparing to the rise ratio in other Altcoins.
• So, Ether and some other Altcoins like Steem usually increases more in its percentage.
• I think the reason that more people have to buy Bitcoin first before they can exchange to steem for example.
  On the other hand, the down in USD / Euro also shows an extra unit true value will be back again after USD get stronger again ( but of course this is not a very influence , but has to be mentioned I think.