They hope to make big 'gains' in Congress in the coming election. [=they hope that many more members of their party will be elected to Congress]
Her hard work 'gained' her their respect. [=she has gained their respect through hard work; they respect her now because of her hard work]
a stock that was one of the year's biggest 'gainers' [=one of the stocks that increased the most in value]
(..) -You mean killed. -It may have information on Skynet. l know he's not the enemy. I've been shot at by the enemy. That's not him. That machine saved you only to gain access to kill all of us. KYLE: We're gonna be okay. Don't worry. BARNES: For my brother. [GUN SNAPS SHUT (..)2009 Terminator Salvation