My brother applied for a US Diversity visa in year 2014 and he was refused with his partner on Misrepresentation of information. Will that affect his visa application to UK? If yes, how can he overcome this issue?
The US and the UK share immigration and visa data under the Five Eyes Alliance. Thus, the UK will know about your brother's US visa refusal.
Your brother should complete his UK visa application completely, admitting he was refused a visa to the US. He can explain - from his own point of view - what occurred. His statements should be concise, factually correct, and non-emotional.
UKVI may issue him a UK visa, or he may be refused. No one here can predict the outcome.