You might feel like you want/need his 'permission' to keep 'his' baby, but you really, really don't. Yes, it is his baby & I think it's fair enough for him to tell you how he feels about it - but it's also YOUR baby and on top of that, it is YOUR body. It is YOU that has to live with this decision, it is YOUR body that has to go through this (either the termination or the pregnancy), not his. It is very very unfair of him to put you under pressure to terminate your pregnancy :(
He might even lower himself to say will 'dump' you if you keep it - if he does say that, then dump his stupid arse now - whatever you decide about the baby.
Even if you do terminate your pregnancy in the hope of 'keeping him', it is unlikely to work out, you would feel an enormous amount of resentment and it is bound to destroy your relationship.
If it was me and he was putting me under pressure to terminate I would leave him now and I would tell him that I intended to continue with my pregnancy.
Think carefully about what YOU want, what is right for YOU. 5 weeks is very very early and it really is, at the moment 'a cluster of cells' (for want of a better phrase) and not yet a baby. You have your whole life ahead of you - is this the right time for YOU (not him, YOU) to be having a baby? For some it's the making of them for others waiting is a better option - only YOU can decide what is right for YOU.