can we claim itc on mutual fund commission

Yes , ITC available on commsion

per section 24 CGST act ( compulsory registration)

vii] persons who make taxable supply of goods or services or both on behalf of other taxable persons whether as an agent or otherwise;

AND

As per definition of agent
Section 2(5) of The Central Goods and Services Tax Act, 2017 provides for definition of agent as follows: “agents” means a person including a factor, broker, commission agent, arhatia, del credere agent, or an auctioneer or any other mercantile agent, by whatever name called, who carries on the business of supply or receipt of goods or services or both on behalf of another.

So Agent has to registered irrespective of turnover

Yes, you can claim ITC on commission and compulsory registration is must.