He lied to the VP about having the conversations with the Russians. That is the crux of the issue.
He didn’t lie that he had conversations. The question is the content. The accusation is that he denied about discussing sanctions, but when you look at the NYT, WaPo, and WSJ, he never said sanctions would be lifted. He basically said to hold off on retaliating and gave “an impression” that the sanctions would be lifted. The WSJ doesn’t even go that far as to say he gave an impression. Overall, he said that things could be reviewed when Trump got in.
I think it’s stretching it to say that he told a big lie or thought what he said was a big deal. What has been printed as being said in the NYT, WaPo, and WSJ doesn’t come off to me like a big deal.
He couldn’t have told them that they were lifting the sanctions because the sanctions are still in place and will be per Nikki Haley.