it's not the same giant

The smith died in Anor Londo at his anvil

SPOILER ALERT
No , its gough from dark soul 1 dlc , it is pretty obvious. as for the giant black smith in dark soul 1, you will fin him later dead in anor Londo

Unfortunately you find the giant smith elsewhere in the game in a very familiar location, but also very sad situation.

I think if you chose the White Branch as your burial gift he already starts as friends, and you don't have to talk to him first

OP here. I found that if i spoke to him once again he would align with me again.

i don't know what triggers the giant dying but i can confirm that he does not kill Onionbro

Patches does not kill either of them (he MIGHT kill another NPC thou).

Lies, Patches is your very bestest friend, he would never harm anyone and he sells most ultimate leather armor as described in description... Just ignore the stats they lies to you too.

What do you mean by "too late" , i haven't met patches yet and the giant died :(. Is there a time limit or is it level based ?

Take a good look at Hawkeye Goughs bow...

He is not Hawkeye Gough as this giant is born far into the future and Gough is from way into the past. Though this giant could be a descendant.

Quite possible, I didn't think the giant is gough but somehow related because of all his stuff, tbh though there are so many references in this game that I find it quite hard to figure out if something is more like an easter egg or if there is an actual canonnical connection.

well after looking up the bow on google image search I still think they look quite similar, in fact the arrows from the DS1 image I found look like the arrows fired by the giant in DS3 so I feel that they really are connected or that it is at least a reference to hawkeye and the smith from anor londo (who gough mentions in his dialogue), doesn't mean it really is that bow but the arrows, the giant and the ring are quite strong implications.

Getting the branches shows him that you've most likely cleared every area where he can help you, so his job is done and he can die in peace I guess and give you his ring... which Hawk Ring is amazing for those whom can't OHKO headshot those *****ed enemies outside of sniping range with DSGB or DSB.... cause Pharis Bow is ***** (looking at you useless weapon art) and Onislayer is for DEX build, not quality.