The 23-year-old posted a video on YouTube last week, in which she asks out the Forgetting Sarah Marshall star by playing the guitar and singing.
Segel accepted Gill's invite, treating her and her twin sister to the Chicago Film Critic Awards show.
"I was freaking out for, like, two days," Gill told the Huffington Post after she got a call from Segel's publicist.
"He came off the elevator, I had my sister with me and he didn't know I had a twin," Gill continued. "So he saw her first and he was like, 'Hey!' And she was like, 'No, I'm not her, that's Chelsea.' He was really tickled by that."
The aspiring actress went on to insist that she wasn't trying to become famous when she posted the video.
"I did not do this to try to get famous. I wanted to be really respectful," Gill said. "It was one of those things where I know I wrote this video and I'm so glad he liked it and we got along so well.
"But he's this busy guy doing his own thing and I'm so humbled and touched that he would take time out of his busy schedule just to get a drink with me," she finished.
Segel is expected to attend Wednesday's (January 11) People's Choice Awards in Los Angeles.