No, he can't, yet. He must first get a permition from the Macedonian volleyball federation and then from FIVB, too. After that he has to wait 1 year and a half and only after that he can start playing for our NT. For now I know that he already got Bulgarian citizenship, but that's the last thing I heard about his question.
Just a brief remark about Gjorgjev - I am not sure, but I think he has to officially quit connection to any Macedonian national team, junior or senior (if he hasn't already done so) and then wait for maybe a period of like 2 years before he is allowed to join our NT. However, I am saying it once again that I am not 100% certain of these regulations and restrictions. Apart from that the Bulgarian passport is enough to do the trick.
I've also heard that he at least will have to get a permission from the Macedonian Federation to play for Bulgaria, the Bulgarian passport itself is not enough. And the bad news is that the Macedonians don't want to give him the permission, at least that's what I've heard. This is really awful because he can't raise the level of Macedonian volleyball to a higher degree but he can really help our NT. And isn't it most important what the player wants, not what the Federation wants? I'm also sure that after the passport he has to wait 2 years to play for our NT (like all Cuban refugees to play in a foreign club) but I don't know when they start counting those 2 years - after the passport or after the permission. Anyway, I really like to see him in NT because it isn't 100% sure that he has got the skill, but it's 200% sure that he has got the desire and guts to do it, unlike Bratoev, for ex, who always enters the field frightened.