In case of the sentence beginning with " There's a good chance~"
1. There's a good chance you can meet him there
2. There's a good chance you could meet him there.

1. There's a good chance he'll go there
2. There's a good chance he would go there.

What is the difference of those each 2 sentece?

present - past

Question

In case of the sentence beginning with " There's a good chance~"
1. There's a good chance you can meet him there
2. There's a good chance you could meet him there.

1. There's a good chance he'll go there
2. There's a good chance he would go there.

What is the difference of those each 2 sentece?

present - past

Answer

The differences between "can" and "could" and between "will" and "would" do not relate to the expression "there's a good chance that".

In both of your examples, "will" is correct (instead of can, could, and would).  "There's a good chance that" modifies the main statement to make it less than 100% certain.  It's not necessary to modify the sentence further with a modal auxiliary; this would add a little ambiguity, in my opinion.

Answer

They're close, but the second sentence, in both cases, has an element of doubt. Meaning the speaker's not sure whether "he" can physically go "there" due to time constraints, someone kidnapping him, or his car tires blowing out. Let me know if my answer's confusing.