Just to note first about the other answers: the EU Parliament is really not very important. Most decisions are made within the Council, which as said elsewhere, votes based on population weight. The Parliament does seem to exercise real power over the Commission but beyond that...not much.
Germany is influential because they have a large population i.e. high vote weight in the Council AND they lead a bloc of other nations with similar values (Austria, Belgium, Netherlands, etc.).
It is worth noting though: the UK leaving the EU will likely change this (they usually voted with Germany and had a 13% weight of the EU population). Germany will likely retain some moral leadership but, at the very least, a blocking minority vote (35% of population and 4 members) is possible (the most likely scenario is a France/Italy combination with two other minor members).
In this case, the parliament and council are equally important as they both have to adopt identical versions of the proposal as per the ordinary legislative procedure.
Germany is influential because they have a large population i.e. high vote weight in the Council AND they lead a bloc of other nations with similar values (Austria, Belgium, Netherlands, etc.).
It is worth noting though: the UK leaving the EU will likely change this (they usually voted with Germany and had a 13% weight of the EU population). Germany will likely retain some moral leadership but, at the very least, a blocking minority vote (35% of population and 4 members) is possible (the most likely scenario is a France/Italy combination with two other minor members).