No, there is no definite evidence either way yet.
For all we know from the movie, Finn never knew his real parents. They may be anyone. Maybe we will never know them.
So far, I have seen two arguments that support "Finn is Lando's son" theory.
First, Lando is about the only human with dark skin in original trilogy. Some people think that relative rarity of humans with different pigmentation makes them all related in some way. Going down this way of thinking, the "obvious" conclusion is that Finn must be Lando's family - most likely son. The same way of thinking tells us that Finn is son of Han and Sana, dark-skinned female human introduced in comic book.
Second, Lawrence Kasdan (co-writer of new movies) said that "Lando I don’t think is finished in any way, shape, or form".
The first argument ignores Mace Windu, another dark-skinned human, who was introduced in prequel trilogy. Mace Windu, being a Jedi, most likely never had a child, but he must have had some parents and might have some sibling, so maybe that family line eventually lead down to Finn. Out of universe, the whole argument is pretty racist.
The second argument probably reads too much into Lawrence's words. He was also contracted to co-write spin-off about young Han Solo, and we know from Empire Strikes Back that Han and Lando had some history together. Lawrence could as well mean that we will see Lando in spin-off movie.
So, I guess it's up to you to decide which side is more convincing to you. If you look for strong, factual, canonical evidence, then the current answer is that we know nothing about Finn's family.