What is the stance of Evangelion creators (Including but not limited to Hideaki Anno) on the "Death of Author" concept, regarding the series? The Evangelion franchise is full of unknowns, most were never explained or given any "word of god" statement. 

Some examples:


  What Gendo whispered to Ritsuko after: "I truly... (muted)" to prompt her to answer: "Liar!"





  What is real the motivation for Asuka to tell Shinji "気持ち悪い" at the ending of the End?


Hideaki Anno then made this statement:


  We all have to find our own answers.


Can we truly say that they left these blanks intentionally?

What is the stance of Evangelion creators on the "Death of Author" concept, regarding the series?

Please use references.
The answer to your question must be a resounding "Yes, as far as Shinseki Evangelion is concerned, Anno Hideaki and team are firmly in the 'Author is Dead' camp when it comes to explanations for the franchise." The broader context of the quote from Anno that you've provided in your question, goes into more detail:


  Evangelion is like a puzzle, you know. Any person can see it and give
  his/her own answer. In other words, we’re offering viewers to think by
  themselves, so that each person can imagine his/her own world. We will
  never offer the answers, even in the theatrical version. As for many
  Evangelion viewers, they may expect us to provide the ‘all-about Eva’
  manuals, but there is no such thing. Don’t expect to get answers by
  someone. Don’t expect to be catered to all the time. We all have to
  find our own answers.”
  – Anno Hideaki


This is not really surprising, as it's the only stance consistent with the themes and aims of the franchise itself, being based as it is on the philosophical platform of 'postmodern existentialism.' In this schema, there is no such thing as 'objective meaning', only meanings constructed by each individual as a function of their own existence.