Floor speeches are for the constituencies, for the judiciary to understand the reasoning behind the passage of a bill, and sometimes for other audiences (e.g. foreign audiences or large-dollar political donors).
After visiting and seeing the largely empty chamber floors during debate, I had the same question as your second phrasing: "Are any members of congress actually persuaded by the speeches of other members?" So I asked someone who might know: a member of congress who's been serving for decades. He said that he couldn't think of any example from all his years of service where he's even heard of that happening. He then told a story about a very emotional (and well-attended) speech given by one member about the personal effects of something they were voting on, which was quite touching and there might not have been a dry eye in the chamber, but he said "I don't think it changed a single vote." He then gave the answer in my first paragraph above.
Congresspeople are apparently expected to know how they are going to vote before a bill comes up for a vote. Congresspeople are busy meeting with constituents, committees, lobbyists, donors, etc. and taking care of other work much of the time when floor speeches are happening, so a lot of the time they don't even hear the speeches. Sometimes, if they have the floor speeches on the TV in their offices as they're working and they hear some claim (e.g. "Bill X requires Y") that is especially surprising or interesting, they might ask their staff to look into it and find out if that's true.
Congresspeople also rely heavily on their colleagues who are on the committees that go through bills in greater depth, to help them understand bills and the pros and cons thereof. Party/caucus leadership can also be influential in persuading members about how to vote. However, most of those conversations happen on the side or outside of the chamber. There so many other factors that go into deciding how to vote on a bill, which carry far more weight than "what other congresspeople said on the floor," that the latter factor is relatively unimportant.
Short answer to your second phrasing: Generally, no.