Can he force his family to move far away from him so that they will not live in a kaafir land?

Firstly: 

It is not permissible to take lightly the matter of living in a kaafir land, because that has bad effects on the Muslim’s religious commitment and beliefs (‘aqeedah). Hence the Messenger (peace and blessings of Allaah be upon him) warned us against settling among the kuffaar, and he said: “I disavow myself of any Muslim who settles among the mushrikeen.” Narrated by Abu Dawood, 2645; classed as saheeh by al-Albaani in Saheeh Abi Dawood. 

There are some situations in which a Muslim is allowed to stay in a kaafir land, but that is subject to specific conditions, such as the condition that his religious commitment should not be harmed by staying among them. For more information please see questions no. 13363 and 27211. 

Secondly: 

You have to compare the benefits of keeping your family close to you, where you can took after them and serve them and bring them up, and protect yourself from falling into temptation, and the costs of keeping them in that kaafir land, which may affect their religious commitment and attitude, and the costs of your staying there alone, far away from them. You should do this in consultation with your wife, and you should both be keen to fear Allaah, may He be exalted, and to choose that which will please Him. If you think it is better to send them away from that country, and send them back to their Muslim country, then there is nothing wrong with your doing so, and your wife is obliged to obey you. 

The evidence that the wife is obliged to obey her husband – so long as it does not involve sin – is narrated in several texts, such as the report narrated by Ahmad (18233) and al-Haakim from al-Husayn ibn Muhsin, who said that a paternal aunt of his came to the Prophet (peace and blessings of Allaah be upon him) to ask about some need. When he had finished talking to her, the Prophet (peace and blessings of Allaah be upon him) said to her: “Do you have a husband?” She said: “Yes.” He said: “How are you with him?” She said: “I do not fall short in giving him his rights, except that which I am not able to do.” He said: “Look at how you are with him, for he is your paradise and your hell.” The isnaad of this hadeeth was classed as jayyid by al-Mundhiri in al-Targheeb wa’l-Tarheeb, and it was classed as saheeh by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb, 1933. 

And the Prophet (peace and blessings of Allaah be upon him) said: “It is not permissible for a woman to fast when her husband is present except with his permission.” Narrated by al-Bukhaari, 5195. 

Al-Albaani (may Allaah have mercy on him) said, commenting on this hadeeth: If a woman is obliged to obey her husband with regard to his satisfying his desire, then it is more apt that she is obliged to obey him in matters that are more important than that, such as raising their children and paying attention to the well-being of the family, and other rights and duties.” End quote from Adaab al-Zafaaf, p. 282. see also question no. 43123. 

Thirdly: 

The husband may travel and be absent from his family for the purpose of study, work and other legitimate purposes, for no longer than six months. If it will be for longer than that, then he must ask his wife’s permission. The basis for that is that ‘Umar (may Allaah be pleased with him) asked women: “How long can a woman be away from her husband?” They said: “Two months, but in the third month patience decreases, and in the fourth month patience disappears.” He wrote to the commanders of the troops telling them not to keep a man away from his wife for more than four months.  

According to another report: The time for people to be away on campaigns is six months: they travel for a month, then they stay there for four months, then travelling back takes another month. 

See al-Mughni, 7/232, 416. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: There is nothing wrong with a man travelling away from his wife, so long as she is in a secure place, and if he allows him to stay away for more than six months, there is no sin on him. But if she demands her rights, and asks him to come to her, then he should not be away from her for more than six months, unless there is an excuse such as sickness for which he is being treated and the like, because cases of necessity come under special rules. Whatever the case, the wife has the right to decide. If she lets him go and she is in a secure place, then there is no sin on him, even if the husband is away a great deal. End quote. 

Fataawa al-‘Ulama’ fi ‘Ushrat al-Nisa’, p. 106 

And Allaah knows best.