First, I have problems determining the meaning of 伺う. Does it mean "to ask" or "to be told" here?
Second, I just learned about the comparisons with ほど.
There are two patterns I learned:
Now, in context of the dialogue in question, I think that pattern 1 is at play here. Still, considering that I don't really know what the first sentence says, I wonder what to make of this. I also can't find what いやあ means.
Here's my attempt at translation:
A: Have you been told that you're strong at shougi?
B: ? , while I don't boast towards people like that, for the first time already become 40 years.
I also can't make much sense of the second part in the second sentence either