Abhinash, See,to be honest, it is very difficult to predict the cutoffs and the predicted rank of IIT JAM Mathematics, but we can take help from the previous years trends to calculate the expected rank and cutoff. Firstly let us discuss with  respect to the cutoff, then it is a big possibility that you would clear the cutoff irrespective of your category as many coaching institutions predict this years cutoff to be around 23-24, however many coaching institutes' predict it to be close to 20 too.

However, predicting the rank is a bit more difficult task as it also depends on factors like total number of candidates and difficulty level of exam which varies every year and we cannot accurately predict the toughness of this years' paper and its effect on the rank at this instant. However, looking at past few years trends , you can expect a rank close to 285- 340, maybe even less depending on the variables as discussed above. Also, remember that this is the expected ALL INDIA RANK predicted using previous years trends and not your category rank which is very difficult to predict at this point of time.

However, it is still advised that do not rely totally on these predictions as they are largely dependent on previous years trends but these predictions do help us in understanding our chances.