Please check this sentence

[Mr. X]

Hi,

Is this right: I'd say you've been smoking for years.

Is the tense okay here? It is a conversational.

Mr. X

 

[IHIVG]

Hi,

Is this right: I'd say you've been smoking for years.

Is the tense okay here? It is a conversational.

Mr. X

Yes, it's fine.

 

[euncu]

Hi,

Is this right: I'd say you've been smoking for years.

Is the tense okay here? It is a conversational.

Mr. X

***neither a teacher nor a native-speaker***

I'd say, you've been smoking for years.

Unless you're not guessing that he/she is a smoker or not, "would" would sound a bit odd. And I'd put a comma after "I'd say".

Another thing is;
It is conversational. Or, It is a conversation. Furthermore, it actually would be a (small) part of a conversation.

And as for your original question, yes, you used the correct tense.

 

[IHIVG]

Unless you're not guessing that he/she is a smoker or not, "would" would sound a bit odd.

At first glance, it did seem a bit odd to me too. But I paused for a second and thought that it would be the right thing to say in a particular context:

P1: Quit smoking! It's not good for your health!
P2: Oh, come on, I've been smoking only for a couple of weeks!
P1: A couple of weeks?!? I'd say you've been smoking for years!!

 

[euncu]

At first glance, it did seem a bit odd to me too. But I paused for a second and thought that it would be the right thing to say in a particular context:

P1: Quit smoking! It's not good for your health!
P2: Oh, come on, I've been smoking only for a couple of weeks!
P1: A couple of weeks?!? I'd say you've been smoking for years!!

Yes, you're right. But all in all, it's all about guessing.