甚至 and 以至于 — even, and to the point that

规则 甚至 = even — naming the most EXTREME member of a list: 他很忙，甚至周末也不休息。
以至于 = to the point that — the CONSEQUENCE of the degree just stated: 他太累了，以至于走路都在打瞌睡。
The test: after 甚至 comes one more ITEM; after 以至于 comes a RESULT.
甚至 usually takes 也 or 都 later: 甚至连他也不知道。
以至 is the shorter, more formal 以至于.