十分酒 usually serves as an adjectival predicate (e.g., 他是十分酒, 萬分悲) describing the state of having drunk to the full, especially to hilarity. Here, it serves as a noun refering to the maximum amount of alcohol that one can stomach. 瀉白金盂 literally means "to be drained off the silver cup". It is an innovative and interesting way to describe the action of pouring it (= alcohol, the content of the silver cup) into one's stomach.
So, 十分酒瀉白金盂 literally means "The maximum amount of alcohol that one can stomach has been drained off the silver cup." In other words, he has drunk as much as he can. He has drunk to the full. He is completely intoxicated.
Although 十分 reflects "very" in modern Chinese, you should know that its literal and original meaning is "10 out of 10". So you can understand Chinese poems better.
We use 几分 to describe a certain rate of something.
三分醉: 30% drunk
七分醒: 70% awake
八分饱: 80% full
不带有半分遗憾: without any bit of regret
Thanks very much for both answers, which are really helpful. That makes more sense now of his inclusion of 写 in the line. So perhaps "Having drunk to the full from [drained] the silver cup of literature [writing]" (the previous line refers to a jade casket stuffed full of poems).
I am enjoying the challenge of exploring how Tang dynasty poetry uses the language in a much more condensed way and often, of course, with different idiomatic and cultural contexts.
案 refers to a desk (in this context) or a tray (as in 舉案齊眉), not a casket or a box.
堆 means "to pile up".
寫 here does not mean "to write" or "writing". It means 洩 (see 康熙字典). 寫 (音瀉，上聲) and 瀉 (音寫，上聲) are homophones in Middle Chinese, and both can mean 洩. That is, 寫 = 瀉 = 洩.