i don't think a warm winter always has a negative influence

应为does it
这里的has为实义动词所以用does,而前面否定所以反问用肯定
当主语为第一人称I,谓语动词为（don't)think ,believe ,suppose ,expect,imagine,reckon等时,附加部分的主语和谓语动词与宾语从句中的谓语动词和主语保持一致,并用肯定形式.例如：（1）I didn't think he was happy,was he?我认为他并不幸福,是不是?（2）I don't suppose that he cares ,does he?我认为他并不关心,是不是?（3）I think Lucy is a good girl,isn’t she?我认为露西是一个好女孩,不是吗?

does it
I don't think 句型，按照后面从句的谓语动词进行反问
肯定和否定则依照前面确定，所以这里用肯定反问。
不能用has来反问。
因为这里has在句中是实义动词而不是助动词，所以要用does反问而不能用has本身。

i don't think a warm winter always has a negative influence on our life,_isn't it ______?

does it