What is the dictionary form of 깁니다?

I’m learning on Duolingo, and the sentence is 영화가 깁니다. I also use a Memrise deck to help me remember the words, but I always put verbs in their dictionary form. To make sure I’m using the right dictionary form, I look the verb up on Wiktionary. I did so with 깁니다, and assumed it would be 기다, but Wiktionary doesn’t have a page for that. Instead it has a page for 길다, also meaning “to be long,” but with 기다 listed under ‘Alternative forms.’

Is 기다 the same as 길다?

Which is more common, and are they conjugated differently?

Would 길다 be 길습니다 rather than 깁니다?

Thank you for reading this.