Biden made the remarks a day after Secretary of State Antony Blinken met Xi on a trip to China that was aimed at easing tensions between the two countries.
There is an expectation Blinken's visit will pave the way for more bilateral meetings in coming months.
The two leaders discussed bilateral relations and deepening economic ties.
Gates stepped down from Microsoft's board in 2020 to focus on philanthropic works related to global health, education and climate change.
Palestinian Authority President Abbas will be visiting China for three days following China's offer to help revive peace talks with Israel.
The thousands of meters of drilling began in the oil-rich Xinjiang region last Tuesday after the President of China, Xi Jinping, called in 2021 to advance rapidly the exploration of the deep Earth.
Ukraine's foreign minister told Li on Wednesday that Kyiv would not accept any proposals to end the war that involved losing territory or freezing the conflict.
Several foreign missions in China raised the Ukrainian flag, or displayed its image in posters and lights, following the February 2022 invasion.
Ukrainian officials have long been calling on Beijing to use its influence in Russia to help end the war.
China now appears to be stepping in, a year into the war in Ukraine, sensing that the West is not as unified as it appears.