Ok, let's start with an easy one.
Fill in the blank:
"How's it going bros? My name is ......

  Connor Franta
  PEEEEWDIEPIIIIIIE!!!!
  Pewdiepie
  Tobuscus
  Zoella

"Hello once again, Audience!"
Who says that?

  Tyler Oakley
  stampylonghead
  Tobuscus

"Hey what's up you guys, it's ......."
Fill the blank.

  Connor!
  Caspar!
  Zoella!
  PEEEEEEEEWDIEPIIIIIIE!

Who says the following:
"Hello Internet..."

  danisnotonfire
  Superwoman
  Zoella

Who says this?
"Whaddup everyone, it's your girl..."

  Zoella
  Miranda Sings
  Superwoman
  JennaMarbles

What does Miranda Sings say?

  "Hey guys, it's me Miranda!"
  "Hello, it's me Miranda!"
  "It's Miranda here!"

Fill the blank:
"...... guys." (Amazing Phil)

  How are you
  Hey
  Welcome
  Hi

"HELLO, this is....."
Fill the blank!

  Stampy!
  iballisticsquid
  Zoella.

What does nigahiga say?

  Hello, guys!
  Hey everyone!
  Hey guys!
  Hi, my name is Ryan...