Jews do not believe that gathering wood on the Sabbath is or ever was a capital offense.
The account in Torah at Numbers 15:32-34 tells about the stoning of a man who was caught gathering wood on Shabbat, but his sentence doesn't match anything that Jews know about Torah and the Sabbath. According to the Mishna (Shabbat ch.7), gathering is not a type of work forbidden on the Sabbath.
Therefore the account in Numbers is NOT stating that gathering wood is forbidden on the Sabbath (note there is no law that states this in Scripture). The man perhaps was doing something either in the way he gathered wood or the reason why he gathered wood that caused him to be stoned.
People often read this text in Numbers as if this man was old and frail, and he was suffering, perhaps cold, and thus needed wood. But this isn't likely as he was likely surrounded by family and neighbors. The man might have been rich, powerful, and he may have been forcing others to gather wood.
Recall that the account starts out by saying that Israel is in the desert wilderness in verse 32. Why? We know this. They aren't in Egypt and we know they have yet to reach the promised land. Perhaps the man was doing something that caused great hardship, disrespect, and even raised quite a bit of eyebrows in the community. Note that the entire camp of countless Israelites gets involved. Why? How did the camp know that one, single man was gathering wood? Where are the witnesses? Why does verse 34 say there was "no clear decision"? No clear decision about what? The wood? The penalty?
And this is also a short narrative stuck in the middle of laws that have nothing to do with the verse. What gives? Jews don't know.
So no, it is not nor ever has been a capital offense in Israel to gather wood on the Sabbath. The basic principle stands in Judaism that if human need calls for it, the requirements of Sabbath rest are to be broken to avoid hardship.