How would I write: I have known her for 5 years?
Hace conozco cinco anos?
The structure either begins with "hace + period of time + que + present tense of the verb" OR "begins with the present tense of the verb + hace + period of time." I'll give you both so you can see the pattern. You are saying "literally" (word for word) It makes 5 years that I know her.
Hace cinco años que (yo) la conozco.
(Yo) la conoczo hace cinco años.
You need the direct-object "la" for "her."
Sra