Hey I want this as a tattoo for my son and wife and can only find this translation "tha bidh daonnan leibh"
and i dont think it is right

No, that doesn't work: since tha and bidh are two forms of the same verb and wouldn't come one after the other like that.

I'd say instead:
Bidh mi leibh an-còmhnaidh
but you can also use daonnan (especially if you need to avoid accents in the tattoo):
Bidh mi daonnan leibh

Just for future reference, if you were addressing this to just one person, rather than two, the leibh would instead be leat.

Further notes:
-- You may also see bithidh in place of bidh, but either is ok.
-- There is a separate section on this forum for Scottish Gaelic requests, at the bottom of the list of sections. You might want to post any further SG requests there.

_________________
I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

It is addressing two people so it would be leat, anyone want to confirm that this translation is correct?

I confirm Caoimhín's translations

_________________
Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

If you are addressing two people it should be 'leibh', not 'leat'. As stated above, 'leat' is the singular form.

Yes but in Scottish Gaelic, "leibh" can also be used as a formal thing, to speak to one person you don't know well, etc. It's like "vous" in French. But that doesn't exist in Irish! Strangely enough, Irish and Scottish Gaelic ar different on this point. Irish people use "leat" with everybody.

_________________
Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

Yes, I should have mentioned that. The way I usually explain it is as follows:
leat [said to one person, informally]
leibh [said to more than one person, or said formally to one person]

The choice between the informal and formal forms would be a lot like the choice in French between tu and vous or in German between Du and Sie.

_________________
I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.