Working in riba-based banks, insurance companies and breweries is not permissible, and it is not permissible for you to help them in doing evil, whether that is by sending workers to work with them or other ways of helping in committing sin that Allah has forbidden. 

That is because Allah says (interpretation of the meaning):

“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”

[al-Maa’idah 5:2].

Just as Allah has forbidden us to disobey Him, He has forbidden us to help the sinner in his disobedience. 

Muslim narrated in his Saheeh (2674) from Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “Whoever calls others to guidance will have a reward like that of those who follow it, without that detracting from their reward in the slightest. And whoever calls others to misguidance will have a burden of sin like that of those who follow it, without it detracting from their burden in the slightest.” 

Al-Manaawi said:

The one who calls others to good is like the one who does it; if (the one who is called) does that good deed, then he (the one who called him) will have a reward like his, otherwise he will have a reward for calling him. And the one who calls others to evil is like one who does it, because he helped him and he will bear a burden of sin like that of the one who does it, even if he does not do it himself.

End quote from Fayd al-Qadeer, 3/716-717 

Based on that, offering services to help people find jobs in such companies and organizations is not permitted. But with regard to other sectors such as gas and petroleum companies and the like, there is nothing wrong with it. 

The fact that most of the jobseekers are not Muslim does not alter the ruling, because this is helping in something that Allah has made haraam and forbidden to all people. And what is haraam is forbidden to both Muslims and non-Muslims. 

The rulings of sharee‘ah which are addressed to the believers are also addressed to the kuffaar, as is the view of the scholars. 

Al-Nawawi (may Allah have mercy on him) said: 

It should be noted that the favoured view is that the minor issues of sharee‘ah, both commands and prohibitions, are also addressed to the kuffaar. This is the view of the majority of scholars. End quote. 

Shaykh al-Islam (may Allah have mercy on him) was asked about sewing for a Christian a silken belt on which there are gold crosses; is there any sin on the one who sews it? 

He replied: 

Yes, if one helps a man in disobedience towards Allah, he is sinning because he is helping in sin and transgression. If that is the case if one helps in sin, then how about helping in kufr (disbelief) and the symbols of kufr?

End quote from Majmoo‘ al-Fataawa, 22/141. 

The scholars of the Standing Committee said:

 It is well known in Islam that the major and minor issues of sharee‘ah are also addressed to the kuffaar… So it is not permissible for a Muslim to help them in ignoring that which Allah has enjoined upon them. 

End quote from Fataawa al-Lajnah al-Daa’imah, 14/475 

Moreover, these sectors cause a great deal of harm to both Muslims and non-Muslims, so helping those who are in charge of them brings harm to the Muslims too. 

So it is not permissible for you to help anyone in doing evil actions or pointing the way to that. 

What you should do is guide jobseekers to jobs in permissible activities. If that is not possible and you have to direct them towards haraam kinds of work, then you should change your job and find other work that is permissible. “And whosoever fears Allaah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).3. And He will provide him from (sources) he never could imagine” [al-Talaaq 65:2-3]. And whoever gives up something for the sake of Allah, Allah will compensate him with something better than it. 

And Allah knows best.