Our ability in learning a foreign language varies, which means some might remember vocabularies easily while some might not. Some might talk like a native speaker while some just can't. But I believe frequent practice in a good language environment helps a lot. AND the confidence you have in your heart will help you improve quickly.

其实有很多外国人说中文都比大山要好，只是没他那么出名罢了。他有个说相声的师父。

better than a native? is it possible? if somebody will study chinese follow me, i can promise he can speak chinese as good as a native.

Do you know his wife is Chinese? so my suggestion is finding a Chinese girl friend, of course wife is a plus. Just kidding. keep practising.

well,I think u should know that about 50% of Chinese people cannot speak standard mandarin.by"standard"I mean to get the tones right..so it's not really a big deal that dashan speaks better than a native Chinese.