Being a vampire is one of the core aspect of the new DLC. However, I cannot be one because I can't cure myself of lycanthrope. To cure myself, I have to cure Farkas and Vilkas. I have already cured Farkas, but Vilkas refuses to offer me any quest(Not even his Purity quest). This means I am unable to cure myself of lycanthropy.

In youtube, search "Elder Scrolls V Skyrim Glitch Can't Get a Quest From Vilkas or Farkas of the Companions " details exactly my problem. Vilkas only offering 2 dialogue options, "Follow me" and "Train two handed" but no quest dialogue.

I have researched on wiki and forums and found no fix to this issue. Is there a way to fix this using console commands? Please help!

You need to ask questions about Dawnguard in the Dawnguard forum, not here.

Well...this.
But to answer your question. No it won't impact you. By turning into a vampire in Dawnguard, you get cured of lycanthropy.