By looking up what the Kitab al-Miraj was, you can see many similarities to the Divine Comedy: a traveler's journey through the afterlife.
Is it possible that Dante plagiarized this work?
Dante was probably influenced and inspired by various Muslim sources, including the Kitab al-Miraj, but the similarities are not strong enough to claim plagiarism.
This conjecture dates from 1919 and was first proposed by Miguel Asín Palacios, a Spanish priest. His theories, published in La Escatología Musulmana en la Divina Comedia (Islamic Eschatology in the Divine Comedy), were not solely about the Kitab al Miraj, but conjectured that Dante's book was influenced by several strands of Islamic thinking.
In terms of the two books, there are more parallels than the relatively common theme of describing a journey into the afterlife:
Both Miraj and Dante take their journeys while dreaming, encountering a wolf and a lion as they set off.
Both have a divine guide, who describes to the traveller the strange lands they are about to encounter.
The layers of heaven and hell are the same in both books, as are the punishments for some of the sins.
When both travellers stand before God they are blinded and guided forward with prayers by their companions.
It is not an implausible supposition, either. Europe in Dante's time - particularly Spain under Alfonso X - had close ties to the Muslim world. Dante's mentor, Brunetto Latini stayed at Alfonso's court. A number of well-known contemporary scholars including Thomas Aquinas were influenced by Arabic thinking.
There is also evidence that Dante had access to the Kitab al Miraj. During his stay with Alfonso X, Brunetto Latini met Bonaventura de Siena who had translated the book into Latin. It's possible a copy was provided to Latini and from him to Dante, although we have no direct evidence for this.
The expert consensus on the matter, however, appears to be that while Dante was influenced by Islamic sources, The Divine Comedy does not owe a direct debt to the Kitab al Miraj. Some of the parallels are not unique to the latter work but can be found in other sources such as the Hadith and the Resalat Al-Ghufran.
In addition, while there are several notable similarities, they make up only a small part of Dante's work. And some of the crossovers, such as associating God with a blinding light, or with lions and wolves, are common images across the Abrahamic religions.