"甚至可以说" can be translated into English as "one could even say", "it could even be said", or "you could even argue", depending on the context and the tone you want to convey.
For example:
One could even say that this is the most significant discovery of the century. （甚至可以说这是本世纪最重要的发现。）
It could even be said that his contribution is irreplaceable. （甚至可以说他的贡献是不可替代的。）
You could even argue that this approach is more efficient. （你甚至可以说这种方法更有效。）